floppy: Run floppy initialization asynchronous

floppy_init is quite slow, 3s on my test system to determine
that there is no floppy. Run it asynchronous to the other
init calls to improve boot time.

[jkosina@suse.cz: fix modular build]

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>