Fix a BM control -related panic by bringing rev 1.44-1.45

Fix a BM control -related panic by bringing rev 1.44-1.45
of acpi_cpu.c from FreeBSD:
 revision 1.45
 date: 2004-10-11 21:15:10 +0000;  author: njl;  state: Exp;  lines: +28 -16;
 Update C3 support when BM control is not present.

 * Fix a bug where caches were flushed on non-C3 transitions.
 * Be sure a working flush cache instruction is present before using it.
 * Disable C3 completely if it isn't present.
 ----------------------------
 revision 1.44
 date: 2004-10-11 06:06:42 +0000;  author: njl;  state: Exp;  lines: +28 -17;
 If bus mastering control is not available (PM2_BLK), don't just disable
 C3.  Instead, flush caches before entering C3.  This may be slower but
 provides good power savings.

Reported-by: Richard Nyberg <rnyberg at murmeldjur.se>