cpu/arm/k60: system_MK60D10.c indentation fix.

Reduced to 2 spaces.

Signed-off-by: Joakim Gebart <joakim.gebart@eistec.se>
cpu/arm/k60: Fix SystemCoreClockUpdate() for rev.1

SystemCoreClockUpdate needs ifdefs to handle both versions of the MCG
module.

Signed-off-by: Joakim Gebart <joakim.gebart@eistec.se>