ksp5012: revert i2c3 bus speed to 100kHz

This is done specifically to make the behavior on .A2 boards
more consistent with the LIBs PIC.

Signed-off-by: Russell Robinson <rrobinson@phytec.com>
Merge remote-tracking branch 'rdrjr-phytect/WIP/rrobinson@phytec.com/4AJ.2.5P2' into newkernel