MSI: Rename PCI_CAP_ID_HT_IRQCONF into PCI_CAP_ID_HT

0x08 is the HT capability, while PCI_CAP_ID_HT_IRQCONF would be
the subtype 0x80 that mpic_scan_ht_pic() uses.
Rename PCI_CAP_ID_HT_IRQCONF into PCI_CAP_ID_HT.

And by the way, use it in the ipath driver instead of defining its
own HT_CAPABILITY_ID.

Signed-off-by: Brice Goglin <brice@myri.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>