mwl8k: allow more time for firmware commands to complete

Some firmware commands can under some circumstances take more than 2
seconds to complete.  This patch bumps the timeout up to 10 seconds,
and prints a message whenever a command takes more than 2 seconds.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>