uboot: apply xtensa overlay

Xtensa core configuration must be added to U-Boot before it can be
built for that xtensa CPU variant. Extract configuration files from the
xtensa overlay as is done for other packages that need to be configured
for a specific xtensa core.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

arch/arch.mk.xtensa

@@ -23,7 +23,8 @@ endif
 # arch-xtensa-overlay-extract -- extract an extensa overlay
 #
 # argument 1 is the path in which to extract
-# argument 2 is the component to extract, one of: gcc, binutils, gdb, linux
+# argument 2 is the component to extract, one of: gcc, binutils, gdb, linux,
+#            u-boot
 #
 # Example:
 #   $(call arch-xtensa-overlay-extract,/path/to/overlay.tar,$(@D),gcc)

boot/uboot/uboot.mk

@@ -153,6 +153,14 @@ endef
 UBOOT_POST_EXTRACT_HOOKS += UBOOT_COPY_OLD_LICENSE_FILE
 UBOOT_POST_RSYNC_HOOKS += UBOOT_COPY_OLD_LICENSE_FILE
 
+ifneq ($(ARCH_XTENSA_OVERLAY_FILE),)
+define UBOOT_XTENSA_OVERLAY_EXTRACT
+	$(call arch-xtensa-overlay-extract,$(@D),u-boot)
+endef
+UBOOT_POST_EXTRACT_HOOKS += UBOOT_XTENSA_OVERLAY_EXTRACT
+UBOOT_EXTRA_DOWNLOADS += $(ARCH_XTENSA_OVERLAY_URL)
+endif
+
 # Analogous code exists in linux/linux.mk. Basically, the generic
 # package infrastructure handles downloading and applying remote
 # patches. Local patches are handled depending on whether they are