bsps/sparc: Remove fix for ERC32 with FPU rev. B/C
bsps/sparc: Add missing IRQMP registers
bsp/leon3: Use interrupt timestamping counter

Use the interrupt controller timestamping counter for the CPU counter if
available since it runs with a high frequency.
arm: Fix stack alignment in interrupt handler

According to AAPCS, section 5.2.1.2, "Stack constraints at a public
interface" the stack must be 8 byte aligned.  This was not the case
during interrupt processing.