drm/amd/amdgpu: enable W=1 for amdgpu

We have a clean build with W=1 as of
commit c168feed ("drm/amd/display/amdgpu_dm/amdgpu_dm_helpers: Move
SYNAPTICS_DEVICE_ID into CONFIG_DRM_AMD_DC_DCN ifdef"). So, let's enable
these checks unconditionally for the entire module to catch these errors
during development.

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/Makefile

@@ -40,7 +40,18 @@ ccflags-y := -I$(FULL_AMD_PATH)/include/asic_reg \
 	-I$(FULL_AMD_PATH)/amdkfd
 
 subdir-ccflags-y := -Wextra
-subdir-ccflags-y += $(call cc-option, -Wunused-but-set-variable)
+subdir-ccflags-y += -Wunused
+subdir-ccflags-y += -Wmissing-prototypes
+subdir-ccflags-y += -Wmissing-declarations
+subdir-ccflags-y += -Wmissing-include-dirs
+subdir-ccflags-y += -Wold-style-definition
+subdir-ccflags-y += -Wmissing-format-attribute
+# Need this to avoid recursive variable evaluation issues
+cond-flags := $(call cc-option, -Wunused-but-set-variable) \
+	$(call cc-option, -Wunused-const-variable) \
+	$(call cc-option, -Wstringop-truncation) \
+	$(call cc-option, -Wpacked-not-aligned)
+subdir-ccflags-y += $(cond-flags)
 subdir-ccflags-y += -Wno-unused-parameter
 subdir-ccflags-y += -Wno-type-limits
 subdir-ccflags-y += -Wno-sign-compare