download/u-boot: Support applying patches from board dirs

Boards may need different sets of patches to be applied to their U-Boot
builds, copy the existing mechanism from the coreboot download script to
the U-Boot download script.

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>

resources/scripts/download/u-boot

@@ -169,6 +169,20 @@ downloadfor() {
 			"${ubtree}"
 		return 1
 	fi
+
+	for patch in resources/u-boot/${board}/patches/*.patch; do
+		if [ ! -f "${patch}" ]; then
+			continue
+		fi
+
+		git -C "${ubtree}" am "$(pwd)/${patch}" || touch build_error
+		if [ -f build_error ]; then
+			printf "ERROR: %s: Unable to apply patch '%s' for board '%s' on tree '%s'" \
+				"download/u-boot" "${patch}" "${board}" "${ubtree}"
+			git -C "${ubtree}" am --abort
+			return 1
+		fi
+	done
 }
 
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