drm/i915/uc: Reject duplicate entries in firmware table

drm/i915/uc: Reject duplicate entries in firmware table

It was noticed that duplicate entries in the firmware table could cause
an infinite loop in the firmware loading code if that entry failed to
load. Duplicate entries are a bug anyway and so should never happen.
Ensure they don't by tweaking the table validation code to reject
duplicates.

For full m/m/p files, that can be done by simply tweaking the patch
level check to reject matching values. For reduced version entries,
the filename itself must be compared.

v2: Improve comment (review by Daniele)

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230502234007.1762014-6-John.C.Harrison@Intel.com