firmware: xilinx: zynqmp: Remove unused macro

ZYNQMP_PM_CAPABILITY_POWER capability is not supported by firmware
and hence needs to be removed

Signed-off-by: Tejas Patel <tejas.patel@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Jolly Shah <jolly.shah@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>