Makefile: don't add -Wno-maybe-uninitialized twice

Avoid adding the same flag to KBUILD_CFLAGS twice.

Fixes: 8602d97ca2cf ("Makefile: avoid false positive -Wmaybe-uninitialized")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
diff --git a/Makefile b/Makefile
index 2fcb704..769d9b8 100644
--- a/Makefile
+++ b/Makefile
@@ -717,7 +717,7 @@
 endif
 
 ifdef CONFIG_CC_OPTIMIZE_FOR_DEBUG
-KBUILD_CFLAGS	+= -Og -Wno-maybe-uninitialized
+KBUILD_CFLAGS	+= -Og
 # Avoid false positives -Wmaybe-uninitialized
 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394
 KBUILD_CFLAGS	+= -Wno-maybe-uninitialized