MFC r261570, r261572

  Revert r260440 (add USB_HOST_ALIGN to all configs, it's only needed for
  platforms with a 64-byte cacheline size).

  Add option USB_HOST_ALIGN=64 for all SoCs that have 64 byte cache lines.
MFC r256871, r259034, r266010

r256871:
Implement watchdog function and register it with watchdog list.

r259034:
Make the sysctl node read-only.

r266010:
Remove extra newlines.
No functional changes.
MFC r265876:
  In cf_get_method, when we don't already know what clock speed the CPU is
  running at, guess the nearest value instead of looking for a value within
  25 MHz of the observed frequency.

  Prior to this change, if a system booted with Intel Turbo Boost enabled,
  the dev.cpu.0.freq sysctl is nonfunctional, since the ACPI-reported
  frequency for Turbo Boost states does not match the actual clock frequency
  (and thus no levels are within 25 MHz of the observed frequency) and the
  current performance level is read before a new level is set.

Relnotes:	Bug fix in power management on CPUs with Intel Turbo Boost
MFC r259270

After r266105 ofw_iicbuc.c will be built by default for any kernel which
includes options 'iicbus' and 'fdt'.  Remove the (now) unnecessary entries.