generic: add linux 4.1 support

Boot tested: http://pastebin.com/L6aAb9xj



Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
[jogo:
  update to 4.1 final
  add patches added since submission
  delete patches applied in later rcs
  restore commit messages in 220-gc-sections and 304-mips_disable_fpu
  fix 050-backport_netfilter_rtcache to match new API
  update inlined dma ops with upstream changes
  add missing config symbols
  enabled CONFIG_MULTIUSER
  update kmod defintions for 4.1
]
Signed-off-by: Jonas Gorski <jogo@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@46112 3c298f89-4303-0410-b956-a3cf2f4a3e73