drm/xe/xe_uc_fw: Use firmware files from standard locations

drm/xe/xe_uc_fw: Use firmware files from standard locations

The GuC/HuC firmware files used by Xe drivers are the same as
used by i915. Use the already-known location to find those
firmware files, for a couple of reasons:

1. Avoid having the same firmware placed on two different
   places on MODULE_FIRMWARE(), if both 915 and xe drivers
   are compiled;

2. Having firmware files located on different locations may end
   creating bigger initramfs, as the same files will be copied
   twice my mkinitrd/dracut/...;

3. this is the place where those firmware files are located at
   https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git
   Upstream doesn't expect them to have on other places;

4. When built with display support, DMC firmware will be
   loaded from i915/ directory. It is very confusing to have
   some firmware files on a different place for the same driver.

Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Lucas de Marchi <lucas.demarchi@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Thomas Hellstrom <thomas.hellstrom@linux.intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
[ Mostly agree with the direction of "use the firmware blobs from
  upstream at their current location for these platforms". Previous
  directory was not wrong as the plan was to have it handled in the
  upstream firmware repo. For future platforms the location can be
  changed if the support is only in xe ]
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20230310081338.3275583-1-mauro.chehab@linux.intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>