EfikaMX: Adjust undocumented magic constant in config file

This magic constant with zero documentation, when it's last 8 bits are set to
0x45, configures correctly the PERCLK dividers. Therefore the I2C operates
correctly when divider computed from PERCLK.

Note: This constant is written to CBCDR register in
arch/arm/cpu/armv7/mx5/lowlevel_init.S, but it's written only once. The register
is accessed three more times in the file, with different values written to it
each time.

Signed-off-by: Marek Vasut <marek.vasut@gmail.com>