brcmfmac: reduce allocations needed during nvram data download

The nvram data is preprocessed before being sent to the device
and just before sending an additional allocation was done that
assured word alignment of the data. This has moved to the
preprocessing step to reduce allocations and subsequent copying
of the nvram data.

Reviewed-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>