unused since MI MBR handling commit in 2007

Index: sys/sys/disklabel.h
===================================================================
RCS file: /cvs/src/sys/sys/disklabel.h,v
diff -u -p -r1.86 disklabel.h
--- sys/sys/disklabel.h	7 Nov 2022 10:33:22 -0000	1.86
+++ sys/sys/disklabel.h	28 Oct 2024 02:00:27 -0000
@@ -458,10 +458,6 @@ struct dos_partition {
 	u_int32_t	dp_size;	/* partition size in sectors */
 };
 
-/* Isolate the relevant bits to get sector and cylinder. */
-#define	DPSECT(s)	((s) & 0x3f)
-#define	DPCYL(c, s)	((c) + (((s) & 0xc0) << 2))
-
 /* Known DOS partition types. */
 #define	DOSPTYP_UNUSED	0x00		/* Unused partition */
 #define	DOSPTYP_FAT12	0x01		/* 12-bit FAT */