This patch fixes the unbalanced calls to enable_irq_wake() and
disable_irq_wake() in the AT91 (and AVR32) serial driver.

It should resolve these kernel messages:
  Unbalanced IRQ x wake disable
  BUG: warning at kernel/irq/manage.c:167/set_irq_wake()

Original patch from Marc Pignat.
Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>