You can't view a RAW image, because a RAW file is not an image, it is a set of monochrome luminance values. When the data is converted to RGB using demosaicing certain settings such as contrast, saturation, etc. are applied. There has to be a value for those settings. You are much better off learning to use the histogram (also drawn from the JPEG preview) to judge exposure rather than looking at the brightness of the LCD screen. A perfectly exposed image can look grossly overexposed if the LCD screen is at the brightest setting when you are in a darker environment, and I suspect this has more to do with your exposure problem than which picture style is selected.
The closest you can probably get to what you want is to select the neutral picture style. But be aware the images will look flat until you add some contrast, saturation, and work your light curves in post processing.
Here's an image of a scene with a very wide dynamic range when rendered with some highly customized light curves and +1.17 stops brightness adjustment to raise the shadows and then reign the highlights back in a little.
Here is the same RAW file rendered with a fairly standard set of curves: the neutral picture style and no brightness adjustment.
Here is the same RAW file rendered linearly (no curve). The reason the gamma correction line is curved (in the shape of a near perfect curve for y=(√2)^x when x is between -10 and +4) in the histogram is because the exposure stop scale is exponential - there is really twice as much distance between each set of two stops as you move to the right as there was between the previous two stops. If the exposure scale were rendered that way, then the response "curve" you see would be a straight diagonal line.
I think it is obvious why the camera makers do not allow images to be rendered linearly on the rear LCD screen. But notice that the shape of the histogram is identical in the neutral and linear conversions. It is the response curve that has changed. Also notice that the very small totally saturated area is not very accurately indicated at the right edge in both the neutral and linear gamma correction histograms.
Closeup of the linear histogram.
Here is the final edited image after some additional, fairly aggressive tone mapping has been applied using Canon's DPP HDR module to the single RAW file as originally edited with the customized light curves.
Addendum (In response to comments below by user1207217)
Based on the following images, it is fairly certain the histograms rendered in DPP from raw files are based on a non-gamma corrected, linearly rendered TIFF preview embeded in each .cr2 file created by a Canon EOS camera.
The small (160x120) JPEG thumbnail preview:
There is also a full size JPEG preview image embeded in each .cr2 file that appears to have the exact same processing applied as the thumbnail, other than the obvious resizing.
And the slightly larger (592x395) TIFF preview (rendered as an unedited jpeg):
You can view the actual TIFF here.
