adapter: switch from struct jtag_interface to adapter_driver

To reorganize the adapters code, introduce an adapter_driver
struct that contains all the adapter generic part, while
keeping in two separate struct the specific API jtag_ops and
swd_ops.
Move the allocation of *adapter_driver from the JTAG-specific
file core.c to the more adapter-specific file adapter.c
While splitting the old jtag_interface for every driver, put
the fields in the same order as in the struct declaration so
we keep a consistent code across all the drivers.

While other transport specific API could/would be added as
separate ops, nothing is done here for HLA.

Change-Id: I2d60f97ac514c0dd2d93a6ec9be66fd9d388dad5
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4900
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>

src/jtag/hla/hla_interface.c

@@ -346,10 +346,11 @@ static const struct command_registration hl_interface_command_handlers[] = {
 	COMMAND_REGISTRATION_DONE
 };
 
-struct jtag_interface hl_interface = {
+struct adapter_driver hl_adapter_driver = {
 	.name = "hla",
-	.commands = hl_interface_command_handlers,
 	.transports = hl_transports,
+	.commands = hl_interface_command_handlers,
+
 	.init = hl_interface_init,
 	.quit = hl_interface_quit,
 	.reset = hl_interface_reset,
@@ -358,4 +359,6 @@ struct jtag_interface hl_interface = {
 	.speed_div = &hl_interface_speed_div,
 	.config_trace = &hl_interface_config_trace,
 	.poll_trace = &hl_interface_poll_trace,
+
+	/* no ops for HLA, targets hla_target and stm8 intercept them all */
 };