crypto: xilinx: Handle AES PM API return status

Return value of AES PM API is not handled which may result in
unexpected value of "status" in zynqmp_pm_aes_engine().

Consider "status" value as valid only if AES PM API is successful.

Fixes: bc86f9c5 ("firmware: xilinx: Remove eemi ops for aes engine")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Rajan Vaja <rajan.vaja@xilinx.com>
Link: https://lore.kernel.org/r/1588330354-27942-1-git-send-email-rajan.vaja@xilinx.com


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