firmware: xilinx: check return value of zynqmp_pm_get_api_version()

Currently return value of zynqmp_pm_get_api_version() is ignored.
Because of that, API version is checked in case of error also.
So add check for return value of zynqmp_pm_get_api_version().

Signed-off-by: Rajan Vaja <rajan.vaja@xilinx.com>
Reviewed-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/1633509835-31949-1-git-send-email-rajan.vaja@xilinx.com


Signed-off-by: Michal Simek <michal.simek@xilinx.com>