[S390] Use IPL CLEAR for reipl under z/VM

If we use the CLEAR ipl option, reipl is faster, since then VM can release
the memory, which has been paged out.
Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/ipl.c

@@ -735,10 +735,10 @@ void do_reipl(void)
 	case REIPL_METHOD_CCW_VM:
 		reipl_get_ascii_loadparm(loadparm);
 		if (strlen(loadparm) == 0)
-			sprintf(buf, "IPL %X",
+			sprintf(buf, "IPL %X CLEAR",
 				reipl_block_ccw->ipl_info.ccw.devno);
 		else
-			sprintf(buf, "IPL %X LOADPARM '%s'",
+			sprintf(buf, "IPL %X CLEAR LOADPARM '%s'",
 				reipl_block_ccw->ipl_info.ccw.devno, loadparm);
 		__cpcmd(buf, NULL, 0, NULL);
 		break;