video: tegra: nvmap: deal with read vs write fault

video: tegra: nvmap: deal with read vs write fault

This change modifies the user fault handler to
- allow read access on reserved page
- do not mark pages which are read by cpu as dirty

Bug 1444151
Bug 1444298

Change-Id: Ic0550503fe27ecd179e9d24f09cc344613249be5
Signed-off-by: Sri Krishna chowdary <schowdary@nvidia.com>
Reviewed-on: http://git-master/r/403969
(cherry picked from commit d8c2a9f56bbfbb90d90719a8fcae58e1b6f0df3c)
Reviewed-on: http://git-master/r/405155
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>