Print idcode value in error message.

src/jtag/core.c

@@ -1107,7 +1107,8 @@ static int jtag_examine_chain(void)
 
 		if ((idcode & 1) == 0) {
 			/* Zero for LSB indicates a device in bypass */
-			LOG_INFO("TAP %s does not have IDCODE", tap->dotted_name);
+			LOG_INFO("TAP %s does not have valid IDCODE (idcode=0x%x)",
+					tap->dotted_name, idcode);
 			tap->hasidcode = false;
 			tap->idcode = 0;