sunxi-mali-mainline-driver: add support for building on arm64

Blobs for ARM64 are now available at Bootlin Github and
sunxi-mali-mainline package has been updated to support them.

This commit updates the <pkg>_MAKE_OPTS variable by substituting
CROSS_COMPILE and INSTALL_MOD_PATH with
LINUX_MAKE_FLAGS. LINUX_MAKE_FLAGS already includes CROSS_COMPILE and
INSTALL_MOD_PAT, but also includes the ARCH variable, which is needed
to select the appropriate architecture when building the Mali driver.

Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/sunxi-mali-mainline-driver/sunxi-mali-mainline-driver.mk

@@ -9,9 +9,8 @@ SUNXI_MALI_MAINLINE_DRIVER_SITE = $(call github,mripard,sunxi-mali,$(SUNXI_MALI_
 SUNXI_MALI_MAINLINE_DRIVER_DEPENDENCIES = linux
 
 SUNXI_MALI_MAINLINE_DRIVER_MAKE_OPTS = \
-	KDIR=$(LINUX_DIR) \
-	CROSS_COMPILE=$(TARGET_CROSS) \
-	INSTALL_MOD_PATH=$(TARGET_DIR)
+	$(LINUX_MAKE_FLAGS) \
+	KDIR=$(LINUX_DIR)
 
 define SUNXI_MALI_MAINLINE_DRIVER_USE_APPLY_PATCHES
 	ln -sf $(SUNXI_MALI_MAINLINE_REV)/series $(@D)/patches