FIRMWARE: bcm47xx_nvram: Replace mac address parsing

Replace sscanf() with mac_pton().

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17982/


Signed-off-by: James Hogan <jhogan@kernel.org>