tcl/target: Add K3 basic support

tcl/target: Add K3 basic support

Add basic connection details for AM654 and J721E SoCs from TI.

See AM65x Technical Reference Manual (SPRUID7, April 2018)
for further details: https://www.ti.com/lit/pdf/spruid7

See J721E Technical Reference Manual (SPRUIL1, May 2019)
for further details: https://www.ti.com/lit/pdf/spruil1

See J7200 Technical Reference Manual (SPRUIU1, June 2020)
for further details: https://www.ti.com/lit/pdf/spruiu1

See AM64X Technical Reference Manual (SPRUIM2, Nov 2020)
for further details: https://www.ti.com/lit/pdf/spruim2

Change-Id: Ie5108c6ad6f1304a6bf5b9f81aa9ebd33b8a559d
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-on: http://openocd.zylin.com/5182
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins