mvebu: rename clearfog sysupgrade script and functions

Cosmetic name change of ClearFog sysupgrade script and its functions to
more generic sdcard. This way it won't be confusing for other future
device additions.

Signed-off-by: Tomasz Maciej Nowak <tomek_n@o2.pl>

target/linux/mvebu/base-files/lib/upgrade/sdcard.sh

@@ -0,0 +1,32 @@
+get_magic_at() {
+	local file="$1"
+	local pos="$2"
+	get_image "$file" | dd bs=1 count=2 skip="$pos" 2>/dev/null | hexdump -v -n 2 -e '1/1 "%02x"'
+}
+
+platform_check_image_sdcard() {
+	local file="$1"
+	local magic
+
+	magic=$(get_magic_at "$file" 510)
+	[ "$magic" != "55aa" ] && {
+		echo "Failed to verify MBR boot signature."
+		return 1
+	}
+
+	return 0;
+}
+
+platform_do_upgrade_sdcard() {
+	sync
+	get_image "$1" | dd of=/dev/mmcblk0 bs=2M conv=fsync
+	sleep 1
+}
+
+platform_copy_config_sdcard() {
+	mkdir -p /boot
+	[ -f /boot/kernel.img ] || mount -o rw,noatime /dev/mmcblk0p1 /boot
+	cp -af "$CONF_TAR" /boot/
+	sync
+	umount /boot
+}