block: disable cpqarray in Kconfig

Mike writes:

"cpqarray hasn't been used in over 12 years. It's doubtful that anyone
 still uses the board. It's time the driver was removed from the mainline
 kernel.  The only updates these days are minor and mostly done by people
 outside of HP."

If nobody yells, we'll remove it from the kernel tree completely
for 3.15.

Signed-off-by: Jens Axboe <axboe@kernel.dk>