alpha,arm,mips,power,x86,cpu,sim: Cleanup activate/deactivate

alpha,arm,mips,power,x86,cpu,sim: Cleanup activate/deactivate

activate(), suspend(), and halt() used on thread contexts had an optional
delay parameter. However this parameter was often ignored. Also, when used,
the delay was seemily arbitrarily set to 0 or 1 cycle (no other delays were
ever specified). This patch removes the delay parameter and 'Events'
associated with them across all ISAs and cores. Unused activate logic
is also removed.