MX51: Drop unused header file for mx51evk

As stated in 272017853339f5b9685f9488bdaf5405812d12a4,
the mx51evk has not CPLD and all references must be removed.
This patch drop a .h file that still remains in board
directory.

Signed-off-by: Stefano Babic <sbabic@denx.de>
2 files changed