drm/exynos: hdmi: use drm_display_mode to check the supported modes

This patch renames check_timing to check_mode and removes the
unnecessary conversion of drm_display_mode to/from fb_videomode in
the hdmi driver.

v4:
1) Changed the commit message to add information related to renaming
the callbacks to check_mode.
2) Changed debug message to print 1/0 for interlace mode.

v3:
1) Replaced check_timing callbacks with check_mode.
2) Change the type of second parameter of check_mode callback from void
pointer paramenter to struct drm_display_mode pointer.

v2:
1) Removed convert_to_video_timing().
2) Corrected DRM_DEBUG_KMS to print the resolution properly.

Signed-off-by: Rahul Sharma <rahul.sharma@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>