sparc64: pull retry logic out of tickcmpr_set(), sys_tickcmpr_set()

sparc64: pull retry logic out of tickcmpr_set(), sys_tickcmpr_set()

Pull the retry logic out of tickcmpr_set() and sys_tickcmpr_set() into
C functions tick_rearm() and sys_tick_rearm(), respectively.  There is
nothing wrong with the retry logic in these assembly functions, but
it's better to keep equivalent code similar and this change realigns
the %TICK and %SYS_TICK rearm code with that of the Hummingbird
%STICK.

Tested by miod@ on UltraSPARC I, UltraSPARC II, and UltraSPARC IIe.

Link: https://marc.info/?l=openbsd-tech&m=167175014315419&w=2
ok kettenis@