drm: Make ioctls available for in-kernel clients

Make ioctl wrappers for functions that will be used by the in-kernel API.
The following functions are touched:
- drm_mode_create_dumb_ioctl()
- drm_mode_destroy_dumb_ioctl()
- drm_mode_addfb()
- drm_mode_rmfb()

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180618141739.48151-4-noralf@tronnes.org


Patch-mainline: 20180618141739.48151-4-noralf@tronnes.org @ 18/06/18, 02:17 p.m.
[stalek@codeaurora.org:
1. Move drm_dumb_buffer.c changes to drm_crtc.c
2. Drop some part of code in drm_dumb_buffer.c because of conflicts.
3. Some code change in drm_ioctl.c because of conflict].

Change-Id: I4c8ec11b6336b343ff84f1396ec15b4440f5540c
Signed-off-by: Shubham Talekar <stalek@codeaurora.org>