brcm47xx: b44: detect external phy by bit set in DevControl register

Without this patch we treated only phy addr 30 as an external phy, but 
there is a register to check that. Now we do not have to try to reset 
the switch to check for an external switch.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@38502 3c298f89-4303-0410-b956-a3cf2f4a3e73