drm/vmwgfx: Convert screen objects to the new helpers

This makes it possible to use the same function for surface dirty and
present. Also fixes page flip without events.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>

diff --cc drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
Simple merge

diff --cc drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
Simple merge

diff --cc drivers/gpu/drm/vmwgfx/vmwgfx_kms.h
Simple merge

diff --cc drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c
Simple merge