Make AT91_MCI_ALLOW_OVERCLOCK a real option.  Rename old use 30MHz to this new option.  Only try to use > 25MHz when our best frequency is < 15MHz and overclocking is enabled. Fix minor style chaff.
Make AT91_MCI_ALLOW_OVERCLOCK a real option.  Rename old use 30MHz to
this new option.  Only try to use > 25MHz when our best frequency is <
15MHz and overclocking is enabled. Fix minor style chaff.

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase