MIPS: BCM47xx: Do not read config from CFE

The config options read out here are not stored in CFE but only in NVRAM on
the devices. Remove reading from CFE and only access the NVRAM.  Reading out
CFE does not harm but is useless here.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
To: linux-mips@linux-mips.org
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Patchwork: https://patchwork.linux-mips.org/patch/1845/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>