clockintr: rename CL_CPU_* flags to CQ_* flags

clockintr: rename CL_CPU_* flags to CQ_* flags

The CL_CPU_* flags were originally so-named because they were set from
clockintr_cpu_init(), which was itself named before I had named the
clockintr_queue struct.  It makes more for the flag namespace to match
the struct namespace, so CQ_* is a better flag prefix than CL_CPU_*.

While we're at it, move the CQ_* flag definitions up so they
immediately follow the clockintr_queue structure definition in
sys/clockintr.h.