kconfig: remove redundant NULL pointer check before free()

Passing NULL to free() is allowed and is a no-op.

Remove redundant NULL pointer checks.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/kconfig/confdata.c

@@ -432,8 +432,7 @@ load:
 		case S_INT:
 		case S_HEX:
 		case S_STRING:
-			if (sym->def[def].val)
-				free(sym->def[def].val);
+			free(sym->def[def].val);
 			/* fall through */
 		default:
 			sym->def[def].val = NULL;