interface: define TMS sequence command

For support of SWD we need to be able to clock out special bit
sequences over TMS or SWDIO.  Create this as a generic operation,
not yet called by anything, which is split as usual into:

 - upper level abstraction ... here, jtag_add_tms_seq();
 - midlayer implementation logic hooking that to the lowlevel code;
 - lowlevel minidriver operation ... here, interface_add_tms_seq();
 - message type for request queue, here JTAG_TMS.

This is done slightly differently than other operations: there's a flag
saying whether the interface driver supports this request.  (In fact a
flag *word* so upper layers can learn about other capabilities too ...
for example, supporting SWD operations.)

That approach (flag) lets this method *eventually* be used to eliminate
pathmove() and statemove() support from most adapter drivers, by moving
all that logic into the mid-layer and increasing uniformity between the
various drivers.  (Which will in turn reduce subtle bugginess.)

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

src/jtag/zy1000/zy1000.c

@@ -804,7 +804,16 @@ int interface_jtag_add_pathmove(int num_states, const tap_state_t *path)
 	return ERROR_OK;
 }
 
-
+int interface_add_tms_seq(unsigned num_bits, const uint8_t *seq)
+{
+	/* FIXME just implement this, like pathmove but without
+	 * JTAG-specific state transition checking.  Then update
+	 * zy1000_interface to report that it's supported.
+	 *
+	 * Eventually interface_jtag_add_pathmove() could vanish.
+	 */
+	return ERROR_JTAG_NOT_IMPLEMENTED;
+}
 
 void embeddedice_write_dcc(struct jtag_tap *tap, int reg_addr, uint8_t *buffer, int little, int count)
 {