qemu: Allow more IDE power management.

qemu: Allow more IDE power management.

Made the QEMU IDE disk tolerate more power-mgmt commands, specifically:
        WIN_SETFEATURE(EN_AAM)  - enable automatic acoustic mgmt
        WIN_SETFEATURE(DIS_AAM) - disable automatic acoustic mgmt
        WIN_SETFEATURE(DIS_APM) - disable automatic power mgmt
        WIN_STANDBY
        WIN_SETIDLE1
        WIN_SLEEPNOW1
        WIN_STANDBY2
        WIN_SETIDLE2
        WIN_SLEEPNOW2
        WIN_STANDBYNOW2
These are all essentially no-ops, like existing support for EN_RLA
(enable read lookahead) and WIN_STANDBYNOW1.

This fixes a crash in the SLES9-SP3 64bit kernel when the powersaved
was started (with ACPI or ACM).  This guest really only needs EN_AAM,
DIS_APM, and WIN_SETIDLE1 support, but the others seemed sensible to
include.

I've excluded EN_APM since I'm unsure of what that's agreeing to do.
It's probably ok to include.

Signed-off-by: Ben Guthro <bguthro@virtualiron.com>
Signed-off-by: David Lively <dlively@virtualiron.com>