arm: omap2: fix AM33xx hwmod infos for UART2

The UART2 hwmod structure is pointing to the EDMA channels of UART1,
which doesn't look right. This patch fixes this by making the UART2
hwmod structure to a new structure that lists the EDMA channels to be
used by the UART2.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Vaibhav Hiremath <hvaibhav@ti.com>
[paul@pwsan.com: updated to apply]
Signed-off-by: Paul Walmsley <paul@pwsan.com>