board: ti: am572x-evm: Update pinmux using latest PMT

Update the board pinmux for AM572x-evm using latest PMT[1] and the
board files named am572x_gp_evm_A3a_sr2p0 and am572x_gp_evm_A2b_sr1p1
that were autogenerated on 30th January, 2017 by
"Ahmad Rashed <a-rashed@ti.com>" and "Tom Johnson <thjohnson@ti.com>".

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>