drm/msm: Remove some potentially blocked register ranges

The 0xf400 and 0xf800 ranges are in the RBBM_SECVID block which may
be protected from CPU access. Skip dumping them since they are minimally
useful for debugging and they aren't worth a system hang.

Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>