PR26480 UBSAN: tc-nios2.c:1634 left shift cannot be represented

[Alan Modra]

	PR 26480
	* config/tc-nios2.c (nios2_parse_reglist): Shift 1UL left.

diff --git a/gas/config/tc-nios2.c b/gas/config/tc-nios2.c
index 16695c5c06..0134b15ae0 100644
--- a/gas/config/tc-nios2.c
+++ b/gas/config/tc-nios2.c
@@ -1631,7 +1631,7 @@ nios2_parse_reglist (char *token, const struct nios2_opcode *op)
 	    }
 	}
 
-      mask |= 1 << regno;
+      mask |= 1UL << regno;
       last = regno;
     }