iwlwifi: compile in ACPI support

Now that LinuxKPI supports the lower case Linux ACPI spellings under
LINUXKPI_WANT_LINUX_ACPI we only need to provide the debug macro to
allow us to compile in ACPI support.

This ties into regulatory and will be used, e.g., for 11ax, 11be,
and Per Platform Antenna Gain (PPAG) settings.

Sponsored by: The FreeBSD Foundation
MFC after: 3 days