board: ti: am57xx: Update SR1.1 RGMII0 iodelay timings for x15/GPEVM

Update the timing for RGMII0 interface based on
PCT_DRA75x_DRA74x_SR1.1_v1.3.10 version (Jan 2016). This update
is for SR1.1

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>