mtd: add ability to dump a mtd device

this can be used on nand flashes and will skip bad blocks and run ecc on the
read data before dumping it.

Signed-off-by: John Crispin <blogic@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43500 3c298f89-4303-0410-b956-a3cf2f4a3e73
gemini: update ethernet driver, register ethernet on nas4220 board

Signed-off-by: Roman Yeryomin <roman@advem.lv>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43501 3c298f89-4303-0410-b956-a3cf2f4a3e73