firmware: zynqmp: Handle errors from ipi_req properly

There are multiple errors what can happen in ipi_req but they are not
propagated properly. That's why propage all error properly.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Adrian Fiergolski <Adrian.Fiergolski@fastree3d.com>
Link: https://lore.kernel.org/r/7ac4f3b2104f04c72d287c46d1ccbce20f138fd4.1634309856.git.michal.simek@xilinx.com
diff --git a/drivers/firmware/firmware-zynqmp.c b/drivers/firmware/firmware-zynqmp.c
index d4dc856..7e0acc5 100644
--- a/drivers/firmware/firmware-zynqmp.c
+++ b/drivers/firmware/firmware-zynqmp.c
@@ -164,6 +164,7 @@
 		 * firmware API is limited by the SMC call size
 		 */
 		u32 regs[] = {api_id, arg0, arg1, arg2, arg3};
+		int ret;
 
 		if (api_id == PM_FPGA_LOAD) {
 			/* Swap addr_hi/low because of incompatibility */
@@ -173,7 +174,10 @@
 			regs[2] = temp;
 		}
 
-		ipi_req(regs, PAYLOAD_ARG_CNT, ret_payload, PAYLOAD_ARG_CNT);
+		ret = ipi_req(regs, PAYLOAD_ARG_CNT, ret_payload,
+			      PAYLOAD_ARG_CNT);
+		if (ret)
+			return ret;
 #else
 		return -EPERM;
 #endif