Char: cyclades, clear interrupts before releasing

Without this patch, the driver sometimes causes "IRQXX: Nobody cares".  Fix it
by turning off irqs when releasing.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>