drm/vmwgfx: Switch to mode_cmd2

Surprisingly few changes needed to make it happen. Compile-tested
only. The idea is that this replaces the 2 patches from Ville's big
fb->format patch series as a prep patch. Only impact to later patches
should be the one instace added in this patch where we look at
fb->pixel_format (instead of fb->bpp and fb->depth), so minor
adjustements in the cocci-generated patches needed.

v2: Restore pitch computation in vmw_fb_kms_framebuffer (Sinclair).

Cc: ville.syrjala@linux.intel.com
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: linux-graphics-maintainer@vmware.com
Cc: Sinclair Yeh <syeh@vmware.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161202070740.31689-1-daniel.vetter@ffwll.ch