init: remove pointless Root_* values

Remove all unused defines, and just use the expanded versions for
the SCSI disk majors.

I've decided to keep Root_RAM0 even if it could be expanded as there
is a lot of special casing for it in the init code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230531125535.676098-6-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

arch/alpha/kernel/setup.c

@@ -658,7 +658,7 @@ setup_arch(char **cmdline_p)
 #endif
 
 	/* Default root filesystem to sda2.  */
-	ROOT_DEV = Root_SDA2;
+	ROOT_DEV = MKDEV(SCSI_DISK0_MAJOR, 2);
 
 #ifdef CONFIG_EISA
 	/* FIXME:  only set this when we actually have EISA in this box? */

arch/ia64/kernel/setup.c

@@ -627,7 +627,7 @@ setup_arch (char **cmdline_p)
 	 * is physical disk 1 partition 1 and the Linux root disk is
 	 * physical disk 1 partition 2.
 	 */
-	ROOT_DEV = Root_SDA2;		/* default to second partition on first drive */
+	ROOT_DEV = MKDEV(SCSI_DISK0_MAJOR, 2);
 
 	if (is_uv_system())
 		uv_setup(cmdline_p);

arch/powerpc/platforms/powermac/setup.c

@@ -76,7 +76,8 @@ int pmac_newworld;
 
 static int current_root_goodness = -1;
 
-#define DEFAULT_ROOT_DEVICE Root_SDA1	/* sda1 - slightly silly choice */
+/* sda1 - slightly silly choice */
+#define DEFAULT_ROOT_DEVICE	MKDEV(SCSI_DISK0_MAJOR, 1)
 
 sys_ctrler_t sys_ctrler = SYS_CTRLER_UNKNOWN;
 EXPORT_SYMBOL(sys_ctrler);

include/linux/root_dev.h

@@ -10,14 +10,6 @@ enum {
 	Root_NFS = MKDEV(UNNAMED_MAJOR, 255),
 	Root_CIFS = MKDEV(UNNAMED_MAJOR, 254),
 	Root_RAM0 = MKDEV(RAMDISK_MAJOR, 0),
-	Root_RAM1 = MKDEV(RAMDISK_MAJOR, 1),
-	Root_FD0 = MKDEV(FLOPPY_MAJOR, 0),
-	Root_HDA1 = MKDEV(IDE0_MAJOR, 1),
-	Root_HDA2 = MKDEV(IDE0_MAJOR, 2),
-	Root_SDA1 = MKDEV(SCSI_DISK0_MAJOR, 1),
-	Root_SDA2 = MKDEV(SCSI_DISK0_MAJOR, 2),
-	Root_HDC1 = MKDEV(IDE1_MAJOR, 1),
-	Root_SR0 = MKDEV(SCSI_CDROM_MAJOR, 0),
 };
 
 extern dev_t ROOT_DEV;