linkb_to_host and addon display adapter override onboard display card

[YhLu]

linkb_to_host and addon display adapter override onboard display card

committed.

1. linkb_to_host use bit 10 to find it if linkb to host.
Please refer to in_coherent.c and hypertransport.c

2. Add vga_pri in device.c to make it = add on card instead of onboard vga,
if add on card presents.
Please refer to device.c and pci_rom.c

YH