kbuild: Move -Wtype-limits to W=2

-Wtype-limits is included in -Wextra which is added at W=1. It warns
(among other things) that 'comparison of an unsigned variable `< 0` is
always false. This causes noisy warnings, especially when used in
macros, hence it is more suitable for W=2.

Link: https://lore.kernel.org/lkml/CAHk-=wiKCXEWKJ9dWUimGbrVRo_N2RosESUw8E7m9AEtyZcu=w@mail.gmail.com/Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/Makefile.extrawarn

@@ -35,6 +35,7 @@ KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation)
 # The following turn off the warnings enabled by -Wextra
 KBUILD_CFLAGS += -Wno-missing-field-initializers
 KBUILD_CFLAGS += -Wno-sign-compare
+KBUILD_CFLAGS += -Wno-type-limits
 
 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
 
@@ -66,6 +67,7 @@ KBUILD_CFLAGS += -Wshadow
 KBUILD_CFLAGS += $(call cc-option, -Wlogical-op)
 KBUILD_CFLAGS += -Wmissing-field-initializers
 KBUILD_CFLAGS += -Wsign-compare
+KBUILD_CFLAGS += -Wtype-limits
 KBUILD_CFLAGS += $(call cc-option, -Wmaybe-uninitialized)
 KBUILD_CFLAGS += $(call cc-option, -Wunused-macros)