Since the UART1 register base name is changed from UART1_IPS_BASE_ADDR
to UART1_BASE to align with other i.MX6 chips. Should update the board
configuration header file with the new name.

Signed-off-by: Ye Li <ye.li@nxp.com>
(cherry picked from commit 18019b8f4b65d3261db6488e416eae66a6500316)