drm/i915: drop -Wall and related disables from cflags as redundant

The kernel top level Makefile, and recently scripts/Makefile.extrawarn,
have included -Wall, and the disables -Wno-format-security and
$(call cc-disable-warning,frame-address,) for a very long time. They're
redundant in our local subdir-ccflags-y and can be dropped.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/5ab754ddc2e342c75deb8476275984918e573beb.1697009258.git.jani.nikula@intel.com

drivers/gpu/drm/i915/Makefile

@@ -5,22 +5,20 @@
 
 # Add a set of useful warning flags and enable -Werror for CI to prevent
 # trivial mistakes from creeping in. We have to do this piecemeal as we reject
-# any patch that isn't warning clean, so turning on -Wall -Wextra (or W=1) we
+# any patch that isn't warning clean, so turning on -Wextra (or W=1) we
 # need to filter out dubious warnings.  Still it is our interest
 # to keep running locally with W=1 C=1 until we are completely clean.
 #
-# Note the danger in using -Wall -Wextra is that when CI updates gcc we
+# Note the danger in using -Wextra is that when CI updates gcc we
 # will most likely get a sudden build breakage... Hopefully we will fix
 # new warnings before CI updates!
-subdir-ccflags-y := -Wall -Wextra
-subdir-ccflags-y += -Wno-format-security
+subdir-ccflags-y := -Wextra
 subdir-ccflags-y += -Wno-unused-parameter
 subdir-ccflags-y += -Wno-type-limits
 subdir-ccflags-y += -Wno-missing-field-initializers
 subdir-ccflags-y += -Wno-sign-compare
 subdir-ccflags-y += -Wno-shift-negative-value
 subdir-ccflags-y += $(call cc-option, -Wunused-but-set-variable)
-subdir-ccflags-y += $(call cc-disable-warning, frame-address)
 subdir-ccflags-$(CONFIG_DRM_I915_WERROR) += -Werror
 
 # Fine grained warnings disable