s390/entry: remove unused expoline thunk

Remove __s390_indirect_jump_r13use_r14 expoline thunk unused since
commit fbbdfca5c5 ("s390/entry.S: factor out SIEEXIT macro").

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/kernel/entry.S

@@ -190,7 +190,6 @@ _LPP_OFFSET	= __LC_LPP
 #endif
 
 	GEN_BR_THUNK %r14
-	GEN_BR_THUNK %r14,%r13
 
 	.section .kprobes.text, "ax"
 .Ldummy: