ramips: fix Asus RP-N53 and Lenovo Y1{, S} image names

This patch:
 * fixes typo (rp_n53 -> rp-n53) in Asus RP-N53 image name
 * removes manufacturer from image names for Lenovo Y1{,S} devices

Signed-off-by: Piotr Dymacz <pepe2k@gmail.com>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@46616 3c298f89-4303-0410-b956-a3cf2f4a3e73