tcl/target/ti_k3: Add support for AM261

tcl/target/ti_k3: Add support for AM261

AM261[1] is a optimized cutdown of AM263P SoC. The key difference is
the reduced number of R5F cores which is now dropped down to 2, and
the DIE ID is different from AM263p, but all other definitions are
compatible, so reuse the definition.

[1] https://www.ti.com/product/AM2612

Change-Id: Ib6ca0b59d0b8991df6e4ab349d371187438cb393
Signed-off-by: Shivasharan Nagalikar <shivasharan.nagalikar@ti.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/8792
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-by: Nishanth Menon <nm@ti.com>
Tested-by: jenkins