tcl/target/ti_k3: Convert memory access ap port num as a variable

Convert the memory access ap port num as a variable to allow support
for the AM2x family of K3 SoCs.

Change-Id: Ibd96c94055721f60d95179dab21d014c15b0f562
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/7943
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins

tcl/target/ti_k3.cfg

@@ -66,6 +66,9 @@ set _gp_mcu_cores 0
 # General Purpose MCU power-ap unlock offsets
 set _gp_mcu_ap_unlock_offsets {0xf0 0x60}
 
+# Generic mem-ap port number
+set _mem_ap_num 2
+
 # Set configuration overrides for each SOC
 switch $_soc {
 	am654 {
@@ -423,5 +426,5 @@ if { 0 == [string compare [adapter name] dmem ] } {
 	}
 } else {
 	# AXI AP access port for SoC address map
-	target create $_CHIPNAME.axi_ap mem_ap -dap $_CHIPNAME.dap -ap-num 2
+	target create $_CHIPNAME.axi_ap mem_ap -dap $_CHIPNAME.dap -ap-num $_mem_ap_num
 }