drm/i915/gt/uc: Fix typo in a comment

Fix typo in a comment.

explaination -> explanation

Signed-off-by: Yuichiro Tsuji <yuichtsu@amazon.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250224085638.3500-2-yuichtsu@amazon.com