The following patch to the HP ZX1 GART driver
- adds recognition of the "HWP0007" device (an AGP 8X bridge)
- fixes the use of acpi_get_devices()

The problem with acpi_get_devices() is that it always returns AE_OK,
except when the callback (zx1_gart_probe()) returns a failure.  That
means agp_hp_init() cannot use the status from acpi_get_devices()
to distinguish between (1) an AGP bridge was found and successfully
initialized, and (2) no AGP bridge was found at all.