macintosh: Remove BKL from ans-lcd

macintosh: Remove BKL from ans-lcd

The ans-lcd driver got the cycle_kernel_lock() in anslcd_open() from
the BKL pushdown and it still uses the locked ioctl.

The BKL serialization in this driver is more than obscure and
definitely does not cover all possible corner cases. Protect the
access to the hardware with a local mutex and get rid of BKL and
locked ioctl.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <20091010153349.966159859@linutronix.de>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>