ADIv5 share DAP command support

Get rid of needless and undesirable code duplication for
all the DAP commands (resolving a FIXME) ... there's no
need for coreas to have private copies of that stuff.
Stick a pointer to the DAP in "struct arm", letting common
code get to it.

Also rename the "swjdp_info" symbol; just call it "dap".

This is an overall code shrink.

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

src/target/arm.h

@@ -167,6 +167,12 @@ struct arm {
 			uint32_t value);
 
 	void *arch_info;
+
+	/** For targets conforming to ARM Debug Interface v5,
+	 * this handle references the Debug Access Port (DAP)
+	 * used to make requests to the target.
+	 */
+	struct adiv5_dap *dap;
 };
 
 /** Convert target handle to generic ARM target state handle. */