ARM: dts: keystone-k2l: Add the second gpio bank node

In case of k2l there are 2 more banks with 16 pins each.
Adding the node as the da-vinci driver now supports multiple
banks.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>