acpi: Remove userland bits on non-ACPI platforms

ACPI is only supported on amd64, arm64 and i386. Don't install the
power_profile rc script or devd configuration on other platforms.

This avoids creating a useless FreeBSD-acpi package on those platforms.

MFC after: 2 weeks
Reviewed by: imp
Sponsored by: https://www.patreon.com/bsdivy
Differential Revision: https://reviews.freebsd.org/D56650