Support the installation of character devices via an lkm.

Closes PR# 1716

Submitted by:	jpt@magic.net

sys/kern/kern_lkm.c

@@ -741,6 +741,15 @@ _lkm_dev(lkmtp, cmd)
 			break;
 
 		case LM_DT_CHAR:
+			if ((i = args->lkm_offset) == -1)
+				descrip = (dev_t) -1;
+			else
+				descrip = makedev(args->lkm_offset,0);
+			if ( err = cdevsw_add(&descrip, args->lkm_dev.cdev,
+					&(args->lkm_olddev.cdev))) {
+				break;
+			}
+			args->lkm_offset = major(descrip) ;
 			break;
 
 		default:
@@ -752,11 +761,11 @@ _lkm_dev(lkmtp, cmd)
 	case LKM_E_UNLOAD:
 		/* current slot... */
 		i = args->lkm_offset;
+		descrip = makedev(i,0);
 
 		switch(args->lkm_devtype) {
 		case LM_DT_BLOCK:
 			/* replace current slot contents with old contents */
-			descrip = makedev(i,0);
 			bdevsw_add(&descrip, args->lkm_olddev.bdev,NULL);
 			break;