m68knommu: remove duplicate ColdFire mcf_autovector() code

Each of the ColdFire CPU platform code that used the old style interrupt
controller had its own copy of the mcf_autovector() function. They are all
the same, remove them all and create a single function in the common
coldfire/intc.c code.

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