video: host: fix unbalanced pm_runtime operations

video: host: fix unbalanced pm_runtime operations

In nvhost_module_init(), pm_runtime_enable() is called. But when
unloading kernel driver, nvhost_module_deinit() forget to call
pm_runtime_disable() which will cause unbalanced operation warnings.

Add pm_runtime operations in nvhost_module_deinit(), also drivers
don't need to do pm_runtime operations which will be handled by
nvhost core.

Bug 1421146

Change-Id: I8dbc1c93e051a4cf2151b3ac9acf1bbe2d9eea0b
Signed-off-by: Bryan Wu <pengw@nvidia.com>
Reviewed-on: http://git-master/r/339526
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>