wifi: ath9k: Remove -Warray-bounds exception

GCC-12 emits false positive -Warray-bounds warnings with
CONFIG_UBSAN_SHIFT (-fsanitize=shift). This is fixed in GCC 13[1],
and there is top-level Makefile logic to remove -Warray-bounds for
known-bad GCC versions staring with commit f0be87c4 ("gcc-12: disable
'-Warray-bounds' universally for now").

Remove the local work-around.

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105679



Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20221006192054.1742982-1-keescook@chromium.org