brcm47xx: add initial support for kernel 3.8

This contains the following new bigger changes:
 * new partition parser which still could lake some features or have bugs
 * new nand flash driver
 * using physmap-flash flash driver for parallel flash
 * some changes to the serial flash driver

With these changes OpenWrt starts using more of the mainline flash drivers.


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35632 3c298f89-4303-0410-b956-a3cf2f4a3e73