arm: mach-k3: Move TI dummy keys out of board folder

arm: mach-k3: Move TI dummy keys out of board folder

This file is used to emulate customer keys on TI development board
ecosystems, move it out of board/ directory and into mach-k3. And
change the relative paths to absolute paths in the binman paths.

While at it, drop the reference in verdin-binman file which is
redundant.

Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Acked-by: Manorit Chawdhry <m-chawdhry@ti.com>