MFC: r292943, r292960

- (Ab)use udivx for dividing the u_int pc_cpuid when implementing
CPU_ISSET(), CPU_SET() etc. in sparc64 asm. This approach has the
benefit of not clobbering %y, allowing to revert r222827 and
partially r222828.
- In r222828, CATR() already was changed to use the equivalent of
PCPU_GET(cpuid) instead of the MD module ID for KTR_MASK, so
belatedly also catch up with KTR_CPU and the C side of ktr(9).
Originally, in r203838 CATR() was moved away from directly reading
the module ID or equivalent as that became impractical with other
CPU types than USI/II supported. With r222828 in place, per-CPU
data generally is set up soon enough, though, that employing
PCPU things in ktr(9) also for use during early stages works.
- Unfortunately, an exception to the latter is the ktr(9) use
in pmap_bootstrap(), which actually is run so early that even
checking for bootverbose being set via the loader doesn't work.
Consequently, replace the ktr(9) use in pmap_bootstrap() with
OF_printf(9) and put it under #ifdef DIAGNOSTIC instead.

MFC 261517,261520:
Convert the license on files where I am the sole copyright holder to
2 clause BSD licenses.

MFC 261517,261520:
Convert the license on files where I am the sole copyright holder to
2 clause BSD licenses.