qla2xxx: Remove redundant NULL check before release_firmware() call.

release_firmware() checks for NULL pointers internally so checking
before calling it is redundant.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Acked-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>