Revert "u-boot: Relax KCFLAGS warnings for GCC 15"

This reverts commit 31ff90f2bb0534a957ac34927ed53991ece5e5cd.

Reason for revert: builds fine without disabling specific compiler flags
now that u-boot has been fixed.

Tested: Built all affected machine types.
Google-Bug-Id: 558753346
Change-Id: Idc615f85189a1b81a78ecc9c9d64b5ac9bfbc1d0
Signed-off-by: Bart Van Assche <bvanassche@google.com>
1 file changed