firmware: xilinx: Remove PM_API_MAX value

There is no reason to keep PM_API_MAX around. The commit acfdd185
("firmware: xilinx: Use hash-table for api feature check") removed its
usage that's why it is not used anywhere now.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/86e94593a29a1b5b1958c539a1bfabdd08c0948e.1610959734.git.michal.simek@xilinx.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>