acpi_powerres: D3cold support

Cherry-pick commit 0b76c0a from ACPICA (actypes: Distinguish between
D3hot/cold, and default ACPI_STATE_D3 to D3cold).

The same distinction is made between PCI_POWERSTATE_D3_HOT and
PCI_POWERSTATE_D3_COLD, as they're defined by ACPI (and are asserted
to be the same).

D3cold is essentially the same as D3hot except the power resources are
turned off. Add support for D3cold to acpi_pwr_switch_consumer.

acpi_d_state_to_str replaces the printf("D%d", d_state) pattern,
allowing for "D3hot" and "D3cold" strings to be printed instead of just
"D3".

Reviewed by: markj, ziaee, mckusick (mentor)
Approved by: markj, mckusick (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D48384