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/minidummy/minidummy.c

@@ -24,18 +24,24 @@
 #include <jtag/minidriver.h>
 #include <jtag/interface.h>
 
-struct jtag_interface minidummy_interface = {
-	.name = "minidummy",
+static struct jtag_interface minidummy_interface = {
 	.execute_queue = NULL,
-	.speed = NULL,
+};
+
+struct adapter_driver minidummy_adapter_driver = {
+	.name = "minidummy",
 	.transports = jtag_only,
 	.commands = NULL,
+
 	.init = NULL,
 	.quit = NULL,
+	.speed = NULL,
 	.khz = NULL,
 	.speed_div = NULL,
 	.power_dropout = NULL,
 	.srst_asserted = NULL,
+
+	.jtag_ops = &minidummy_interface,
 };
 
 int interface_jtag_execute_queue(void)