MIPS: BCM47xx: Extend the filling of SPROM from NVRAM

Some members of the struct ssb_sprom where not filled with data available
in the NVRAM. Some attribute names in the NVRAM changed from SPROM version
3 to version 4. This patch was done by analyzing the the pci sprom parser
in the ssb code and some open source parts of the braodcom wireless driver
used on embedded devices.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2365/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>