drm/ofdrm: Convert PCI IDs to CPU endianness for comparing

Properties of 32-bit integers are returned from the OF device tree
as type __be32. Convert PCI vendor and device IDs from __be32 to host
endianness before comparing them to constants. All relevant machines
are old, big-endian Macintosh systems; hence the bug never happened
in practice.

Fixes sparse warnings shown below.

  drivers/gpu/drm/tiny/ofdrm.c:237:17: warning: restricted __be32 degrades to integer
  drivers/gpu/drm/tiny/ofdrm.c:238:18: warning: restricted __be32 degrades to integer
  drivers/gpu/drm/tiny/ofdrm.c:238:54: warning: restricted __be32 degrades to integer

See [1] for the bug report.

v2:
	* convert endianness (Alex)

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/dri-devel/202210192208.D888I6X7-lkp@intel.com/ # [1]
Link: https://patchwork.freedesktop.org/patch/msgid/20221103101627.32502-2-tzimmermann@suse.de