video: tegra: fb: Configure dc from fb

This patch contains following changes:
1. Modify tegra_fb_update_monspecs to select best mode to apply
   on framebuffer, in HDMI hotplug.
2. Add a console_lock to prevent corruption while fbcon running
   in multiple threads.
3. Add a tegra_dc_disable/enable in tegra_fb_set_par to reflect
   the programmed new mode applied on DC.

Bug: 1005399
Change-Id: I133b38b00f25f767afc05549550fecde8d092fb2
Signed-off-by: Shashank Sharma <shashanks@nvidia.com>
Reviewed-on: http://git-master/r/120932
(cherry picked from commit ec7552ef36c0d0979cb31db6d2d4bd54e7f1c9fb)
Reviewed-on: http://git-master/r/140031
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>