firmware loader: use small timeout for cache device firmware

Because device_cache_fw_images only cache the firmware which has been
loaded sucessfully at leat once, using a small loading timeout should
be reasonable.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>