[IRDA]: use mutex instead of semaphore in VLSI 82C147 IrDA controller driver

The VLSI 82C147 IrDA controller driver uses a semaphore as mutex.  Use the
mutex API instead of the (binary) semaphore.

Signed-off-by: Matthias Kaehlcke <matthias.kaehlcke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>