ramips: fix Omnima models, images and profiles names

Official names for supported Omnima products are (as on website):
 * Omnima HPM
 * Omnima MiniEMBWiFi
 * Omnima MiniEMBPlug

This patch changes:
 * board names
 * dts filenames
 * profile names
 * image filenames
 * LED names

for Omnima devices, for consistency.

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

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@46627 3c298f89-4303-0410-b956-a3cf2f4a3e73