MIPS: BCM47XX: Increase NVRAM buffer size to 64 KiB

MIPS: BCM47XX: Increase NVRAM buffer size to 64 KiB

For years Broadcom devices use 64 KiB NVRAM partition size and some of
them indeed have it filled in more than 50%. This change allows reading
whole NVRAM e.g. on Netgear WNDR4500 and Netgear R8000.

Signed-off-by: Rafał Miłecki <[email protected]>
Cc: [email protected]
Cc: Hauke Mehrtens <[email protected]>
Patchwork: https://patchwork.linux-mips.org/patch/9651/
Signed-off-by: Ralf Baechle <[email protected]>