Revert "ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not PREEMPT alone"

This reverts commit 0b52fe2b9c00cca80ca55f63ed8d02af34108a42.
Revert "ARM: Fix undefined instruction exception handling"

This reverts commit 91c90001975833b83e6b1c75c76300a3da0b23e8.