jtag: add '-ignore-version' option

Add a "-ignore-version" to "jtag newtap" which makes the IDCODE
comparison logic optionally ignore version differences.

Update the "scan_chain" command to illustrate this by showing
the "*" character instead of the (ignored) version nibble.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

src/jtag/jtag.h

@@ -156,6 +156,9 @@ struct jtag_tap {
 	/// Number of expected identification codes
 	uint8_t expected_ids_cnt;
 
+	/// Flag saying whether to ignore version field in expected_ids[]
+	bool ignore_version;
+
 	/// current instruction
 	uint8_t* cur_instr;
 	/// Bypass register selected