Don't start ad-hoc games with -Wno-maybe-initialized

Borrowing from Linux commit 78a5255ffb6a ("Stop the ad-hoc games with -Wno-maybe-initialized")
move to have maybe-initialized warnings be handled with building with
W=2 instead of playing more guessing games with newer compilers.
Signed-off-by: NTom Rini <trini@konsulko.com>

Makefile

@@ -683,6 +683,9 @@ KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks)
 # disable stringop warnings in gcc 8+
 KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
 
+# Enabled with W=2, disabled by default as noisy
+KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized)
+
 # change __FILE__ to the relative path from the srctree
 KBUILD_CFLAGS	+= $(call cc-option,-fmacro-prefix-map=$(srctree)/=)