[ARM] 5110/1: PXA SSP: Remember the platform device on probe()

pdev is used later on by dev_printk() so must be set.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>