board: zynqmp: Move zynqmp commands from board/ to arch/

board: zynqmp: Move zynqmp commands from board/ to arch/

The zynqmp cmds.c is currently tied to the board but the commands
contained within are more closely tied to the architecture. To
allow usage of those commands when the architecture is ZynqMP but
the board is not, this change moves the cmds into the arch/ tree.

The source file is renamed to zynqmp.c to reflect the command name
as well.

Signed-off-by: Charlie Johnston <charlie.johnston@loftorbital.com>
Link: https://lore.kernel.org/r/20240410195008.405061-2-charlie.johnston@loftorbital.com
Signed-off-by: Michal Simek <michal.simek@amd.com>