drivers/misc/cs5535-mfgpt.c: fix wrong if condition

Fix the wrong `if' condition for the check if the requested timer is
available.

The bitmap avail is used to store if a timer is used already.  test_bit()
is used to check if the requested timer is available.  If a bit in the
avail bitmap is set it means that the timer is available.

The runtime effect would be that allocating a specific timer always fails
(versus telling cs5535_mfgpt_alloc_timer to allocate the first available
timer, which works).

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Acked-by: Andres Salomon <dilinger@queued.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>