brcm47xx: bgmac: update to version form netdev git repository


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35833 3c298f89-4303-0410-b956-a3cf2f4a3e73
brcm47xx: bgmac: omit the fcs

This fixes #13058 and hopefully #12927


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35834 3c298f89-4303-0410-b956-a3cf2f4a3e73