arm: tegra: fb: Apply new mode even if its current

Set activation of a mode forcefully via setting FB_ACTIVATE_FORCE
flag. Required for stereo modes also.

Bug 1005399
Change-Id: I37872cc2a04abc8774a5f9f9df7d9e90f2c977f6
Signed-off-by: Shashank Sharma <shashanks@nvidia.com>
Reviewed-on: http://git-master/r/122087
(cherry picked from commit 80a7b7b2d10a97427e12884d469a518cc2b5f765)
Reviewed-on: http://git-master/r/140033
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Matthew Pedro <mapedro@nvidia.com>
Tested-by: Matthew Pedro <mapedro@nvidia.com>
Reviewed-by: Winnie Hsu <whsu@nvidia.com>