util/*/Makefile: Rename -W to -Wextra

-W is the old name for -Wextra, so let's rename it to be consistent with
the rest of the utility Makefiles.

Change-Id: I0e50f13d2617b785d343707fc895516574164562
Signed-off-by: Jacob Garber <jgarber1@ualberta.ca>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34455
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>

util/intelmetool/Makefile

@@ -17,7 +17,7 @@ PROGRAM = intelmetool
 CC      ?= gcc
 INSTALL ?= /usr/bin/env install
 PREFIX  ?= /usr/local
-CFLAGS  ?= -O0 -g -Wall -W -Wno-unused-parameter -Wno-sign-compare -Wno-unused-function
+CFLAGS  ?= -O0 -g -Wall -Wextra -Wno-unused-parameter -Wno-sign-compare -Wno-unused-function
 LDFLAGS += -lpci -lz
 
 OBJS = intelmetool.o me.o me_status.o mmap.o rcba.o msr.o