Add alignment hints for e512 ATA drives.

sys/include/disk.h

@@ -42,6 +42,8 @@ struct Disk {
 	vlong size;
 	vlong offset;	/* within larger disk, perhaps */
 	int width;	/* of disk size in bytes as decimal string */
+	int psecsize;
+	int physalign;
 	int c;
 	int h;
 	int s;

sys/include/fis.h

@@ -102,6 +102,7 @@ struct Sfis {
 	uint	sig;
 	uint	lsectsz;
 	uint	physshift;	/* log2(log/phys) */
+	uint	physalign; /* location of lba0 within phys0 */
 	uint	c;		/* disgusting, no? */
 	uint	h;
 	uint	s;