drm/client: Convert drm_client_buffer_addfb() to drm_mode_addfb2()

Currently drm_client_buffer_addfb() uses the legacy drm_mode_addfb(),
which uses bpp and depth to guess the wanted buffer format.
However, drm_client_buffer_addfb() already knows the exact buffer
format, so there is no need to convert back and forth between buffer
format and bpp/depth, and the function can just call drm_mode_addfb2()
directly instead.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Tested-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/4b84adfc686288714e69d0442d22f1259ff74903.1697379891.git.geert@linux-m68k.org