s390/nospec: Correct modules thunk offset calculation

Fix offset calculation when branch target is more then 2Gb away.

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

Author: Vasily Gorbik

arch/s390/kernel/nospec-branch.c

@@ -114,10 +114,10 @@ static void __init_or_module __nospec_revert(s32 *start, s32 *end)
 			type = BRASL_EXPOLINE;	/* brasl instruction */
 		else
 			continue;
-		thunk = instr + (*(int *)(instr + 2)) * 2;
+		thunk = instr + (long)(*(int *)(instr + 2)) * 2;
 		if (thunk[0] == 0xc6 && thunk[1] == 0x00)
 			/* exrl %r0,<target-br> */
-			br = thunk + (*(int *)(thunk + 2)) * 2;
+			br = thunk + (long)(*(int *)(thunk + 2)) * 2;
 		else
 			continue;
 		if (br[0] != 0x07 || (br[1] & 0xf0) != 0xf0)