ramips: Enable sysupgrade for Sitecom WL-351

Sysupgrade works just fine on my Sitecom WL-351 after adding this
oneliner.

Signed-off-by: Tobias Diedrich <ranma+openwrt@tdiedrich.de>

SVN-Revision: 31843

target/linux/ramips/base-files/lib/upgrade/platform.sh

@@ -38,6 +38,7 @@ platform_check_image() {
 	v22rw-2x2 | \
 	wl341v3 | \
 	wl-330n | \
+	wl-351 | \
 	wli-tx4-ag300n | \
 	whr-g300n |\
 	ur-336un |\