Madge Ambassador ATM Adapter driver: Always release_firmware() in ucode_init() and don't leak memory.

Failure to call release_firmware() will result in memory leak in
drivers/atm/ambassador.c::ucode_init().
This patch makes sure we always call release_firmware() when needed,
thus removing the leak(s).

Yes, I know checkpatch complains about this patch, but it was either that
or completely mess up the existing style, so I opted to use the existing
style and live with the checkpatch related flak.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: David S. Miller <davem@davemloft.net>