[ARM] 3217/1: iop331 uarts as platform devices

Patch from Dan Williams

Convert old-style serial devices to platform devices so that printk's are visible during the boot process.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>