dri/intel: Add explicit size parameter to intel_region_alloc_for_fd

dri/intel: Add explicit size parameter to intel_region_alloc_for_fd

Instead of assuming that the size will be height * pitch, have the caller pass
in the size explicitly.

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>