[ARM] 5185/1: Fix spi num_chipselect for lubbock

Change num_chipselect for lubbock ssp master to reflect requirement
of spi subsystem that all buses have at least 1 chip select.

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Acked-by: Eric Miao <eric.miao@marvell.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>