Add AHCI support for Intel 8 Series/C220 Series Chipset Family SATA Controller.

Reference: /n/sources/patch/sdiahci-c220
Date: Wed Jul  9 20:33:18 CES 2014
Signed-off-by: djc@9grid.fr

--- /sys/src/9/pc/sdiahci.c	Wed Jul  9 20:33:01 2014
+++ /sys/src/9/pc/sdiahci.c	Wed Jul  9 20:32:50 2014
@@ -1963,6 +1963,7 @@
 		 * 0x27c4 is the intel 82801 in compatibility (not sata) mode.
 		 */
 		if (p->did == 0x1e02 ||			/* c210 */
+		    p->did == 0x8c02 ||			/* c220 */
 		    p->did == 0x24d1 ||			/* 82801eb/er */
 		    (p->did & 0xfffb) == 0x27c1 ||	/* 82801g[bh]m ich7 */
 		    p->did == 0x2821 ||			/* 82801h[roh] */