gbm: Axe buffer import format conversion table

gbm: Axe buffer import format conversion table

Wayland buffers coming from wl_drm use the WL_DRM_FORMAT_* enums, which
are identical to GBM_FORMAT_*. Similarly, FD imports do not need to
convert between GBM and DRI FourCC, since they are (almost) completely
compatible.

This widens the formats accepted by gbm_bo_import() when importing
wl_buffers; previously, only XRGB8888, ARGB8888, RGB565 and YUYV were
supported.

Reviewed-by: Emil Velikov <emil.velikov@collabora.com>