VIGS: add DRM_IOCTL_SDP_GA_EXEC command support

VIGS: add DRM_IOCTL_SDP_GA_EXEC command support

The ioctl is needed to make ga_copy. Formely it was issued
from userspace using an execbuffer but currently it is done
directly via drmIoctl.

Aditionally it was necessary to import a device-specific
header. It has been placed to

    include/uapi/drm/sdp_drm.h

like in device kernel. The header needs to be updated
whenever the original one is changed.

Change-Id: I6d78309f38b971d5d7014b1972ff2316eee27003
Signed-off-by: Vasiliy Ulyanov <v.ulyanov@samsung.com>
(cherry picked from commit 48b87ee9c5f0b41e96ab0b70c00a88adc8c26648)