kernel: take bcm47xx_nvram.h from kernel and not backports

kernel: take bcm47xx_nvram.h from kernel and not backports

compat-wireless/backports now contains a bcm47xx_nvram.h file to
backport some of the functions in it which are used by the bcmfmac
driver. This file just checks for the kernel versions and provide an
empty implementations on older kernel versions. This is OK on most
systems, but on bcm47xx / bcm53xx systems we want to call the real
functions here. This commit removes the file from backports in our
build process like we do it with the bcma and ssb header files. Instead
we add a recent version into our kernel so all code uses only one
header file. On bcm47xx / bcm53xx the real implementations of this code
will be used.

Reported-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@47467 3c298f89-4303-0410-b956-a3cf2f4a3e73