target/adi_v5_jtag: Add support for 8-bit IR JTAG-DP

As per Arm Debug Interface Architecture Specification (ADIv5.0 to
ADIv5.2), B3.3.1, the JTAG-DP as an IR length of 4 or 8 bits
depending on the ARM implementation. The current code
only support 4-bit and this patch extends the support to 8-bit IR.
Not tested back yet on a 4-bit target.

Change-Id: Ie4f875dc336caf014c6cfced57574b54d0970623
Signed-off-by: Antoine C. <acalando@free.fr>
Reviewed-on: https://review.openocd.org/c/openocd/+/6285
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

src/target/adi_v5_jtag.c

@@ -43,10 +43,10 @@
 /*#define DEBUG_WAIT*/
 
 /* JTAG instructions/registers for JTAG-DP and SWJ-DP */
-#define JTAG_DP_ABORT		0x8
-#define JTAG_DP_DPACC		0xA
-#define JTAG_DP_APACC		0xB
-#define JTAG_DP_IDCODE		0xE
+#define JTAG_DP_ABORT		0xF8
+#define JTAG_DP_DPACC		0xFA
+#define JTAG_DP_APACC		0xFB
+#define JTAG_DP_IDCODE		0xFE
 
 /* three-bit ACK values for DPACC and APACC reads */
 #define JTAG_ACK_OK_FAULT	0x2