If the FIFO of the card is small, many short messages are queued up to
the upper layers and the userspace. This change allows the applications
to set a minimum datalen they want from the drivers.
Create a common control function to avoid code duplication in each
driver.
Signed-off-by: NKarsten Keil <kkeil@linux-pingi.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>