drivers: platform: tegra: camera: shutdown event

drivers: platform: tegra: camera: shutdown event

implement shutdown/suspend/resume functions to avoid i2c failures.
add atomic cam_ref to prevent the conflict scenario of system
shutdown but the user space still atempt to access the driver.

bug 1503230

Change-Id: I3fe58b49c1391dcc312f096c307a0849b829689a
Signed-off-by: Charlie Huang <chahuang@nvidia.com>
Reviewed-on: http://git-master/r/411093
(cherry picked from commit c4a86a3b83dd0e71026b68e410b45897e7e284fc)
Reviewed-on: http://git-master/r/415578
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Frank Chen <frankc@nvidia.com>
Reviewed-by: Mitch Luban <mluban@nvidia.com>