MIPS: BCM47xx: sprom: read values without prefix as fallback

There are bcma based devices like the Linksys E2000 out there, which do
have one ieee80211 core, but no PCIe core and they are using no
prefixes for the sprom. In addition some values like boardtype are
stored without a prefix for the main SoC chip also when they have an
additional PCIe wifi chip with an own boardtype var on some devices.

The Ethernet addresses are now also read out correctly without a prefix
so calling bcm47xx_fill_sprom_ethernet is not needed any more.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Patchwork: http://patchwork.linux-mips.org/patch/4364


Signed-off-by: John Crispin <blogic@openwrt.org>