brcmfmac: firmware: Allocate space for default boardrev in nvram

If boardrev is missing from the NVRAM we add a default one, but this
might need more space in the output buffer than was allocated. Ensure
we have enough padding for this in the buffer.

Fixes: 46f2b38a ("brcmfmac: insert default boardrev in nvram data if missing")
Reviewed-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Cc: stable@vger.kernel.org
Signed-off-by: Hector Martin <marcan@marcan.st>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220131160713.245637-3-marcan@marcan.st