Revert "wifi: ath6k: silence false positive -Wno-dangling-pointer warning on GCC 12"

This reverts commit bd1d129d.

The dangling-pointer warnings were disabled kernel-wide by commit 49beadbd
("gcc-12: disable '-Wdangling-pointer' warning for now") for v5.19. So this
hack in ath6kl is not needed anymore.

Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230724100823.2948804-1-kvalo@kernel.org