m68knommu: add clock creation support macro for other ColdFire CPUs

The clock support code for ColdFire CPUs currently supports those that
have the clock control register PPMCR. Expose the struct clk for all CPU
types and add a definition for all other ColdFire CPU types.

With this we will be able to define simple clock trees for all ColdFire
CPU types, even though they will not be able to be enabled or disabled.
They will be able to report the clock rate.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>