[compiler.h] Migrate many C++ clients of countof to fbl::count_of

The latter is safer in C++, and the former is a namespace violation in
compiler.h that eventually needs to be resolved.

Test: CQ; should be no functional change
Change-Id: I9809b9fe062fd5f07226323035bf094b3f9de798

[zircon][kernel] Use proper time types and overflow-safe arithmetic

This change is preparation for converting zx_time_t and zx_duration_t
from unsigned to signed types (ZX-2100).

1. Fix several places where the wrong time type was used (e.g.
zx_time_t instead of zx_duration_t). Because these are simple typedefs
it's easy to use the wrong one. While it generally doesn't cause a
problem, using the wrong type can be misleading and lead to bugs like
passing a relative time when an absolute time is expected.

2. Update kernel/ and some other parts of zircon to use the new
overflow-safe arithmetic functions from zircon/time.h.

Performance: Ran "/pkgfs/packages/zircon_benchmarks/0/bin/app -p" on
NUC before and after this change. Differences were withing the noise,
some slightly faster, some slightly slower.

Test: CQ

ZX-2100 #comment cleanup before conversion

Change-Id: I75d074e5850ade5385decd9bbf330497bf7610e9

[clock] zx_clock_get(ZX_CLOCK_MONOTONIC) -> zx_clock_get_monotonic()

Test: no functional change

Change-Id: Iaa513c521d96b178458acc707be3646067971701

[dev][intel-hda] intel-audio-dsp driver

Currently just boots the DSP and loads the firmware.
The DSP driver is independent from the HDA driver, however
the source is checked in under system/dev/audio/intel-hda/
to be consistent with HDA codecs.

Change-Id: Ic2d9bca68ae7ee6c9011f53d0f894b7a68e43b86

[ulib][intel-hda] move utils from intel-hda driver to ulib/intel-hda

Move PinnedVmo, RefCountedBti and WaitConditionFn to ulib/intel-hda
for reuse by the Intel Audio DSP driver.

Change-Id: I85cb56b3d3a0910c9021800941a87ade40359eae

[ulib][intel-hda] Move intel-hda driver support code to a static library

Change-Id: I1354f676422b7b8632de3e7f63fc653023416180