uio: convert drivers/uio/* to use module_platform_driver()

This patch converts the drivers in drivers/uio/* to use the
module_platform_driver() macro which makes the code smaller and a bit
simpler.

Cc: Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com>
Cc: Magnus Damm <damm@igel.co.jp>
Cc: Amit Chatterjee <amit.chatterjee@ti.com>
Cc: Pratheesh Gangadhar <pratheesh@ti.com>
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>