<dev/acpi/acpivar.h>. Ditto for <dev/sysmon/sysmonvar.h>, <sys/bus.h>,
<dev/pci/pcivar.h>, and <dev/isa/isavar.h>.
Also nuke a lot of unused and invalid headers. Some of these are audibly
provided by standard headers (namely <sys/param.h> and <sys/device.h>), some
have nothing to do with ACPI devices (e.g. <sys/syslog.h>), and some are
nonexistent local includes (e.g. "mpu_ym.h"). Moreoever, try to group the
includes into their respective blocks.
Tested with GENERIC and ALL (i386). No functional change.
