jsm: removing unused spinlock

This patch removes bd_lock spinlock (inside jsm_board structure).
The lock is initialized in the probe function and not used anymore.

Signed-off-by: Breno Leitao <leitao@linux.vnet.ibm.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>