ALSA: fm801: explicitly free IRQ line

Otherwise we will have a warning on ->remove() since device is a PCI one.

WARNING: CPU: 4 PID: 1411 at /home/andy/prj/linux/fs/proc/generic.c:575 remove_proc_entry+0x137/0x160()
remove_proc_entry: removing non-empty directory 'irq/21', leaking at least 'snd_fm801'

Fixes: 5618955c (ALSA: fm801: move to pcim_* and devm_* functions)
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>