fpga: zynqmp-fpga: Correctly handle error pointer

Fixes the following static checker errors:

drivers/fpga/zynqmp-fpga.c:50 zynqmp_fpga_ops_write()
error: 'eemi_ops' dereferencing possible ERR_PTR()

drivers/fpga/zynqmp-fpga.c:84 zynqmp_fpga_ops_state()
error: 'eemi_ops' dereferencing possible ERR_PTR()

Note: This does not handle the EPROBE_DEFER value in a
special manner.

Fixes commit c09f7471127e ("fpga manager: Adding FPGA Manager support for
Xilinx zynqmp")
Reported-by: Dan Carpenter <[e-mail]>
Signed-off-by: Moritz Fischer <[e-mail]>
Acked-by: Alan Tull <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/fpga/zynqmp-fpga.c

···
 	char *kbuf;
 	int ret;
 
-	if (!eemi_ops || !eemi_ops->fpga_load)
+	if (IS_ERR_OR_NULL(eemi_ops) || !eemi_ops->fpga_load)
 		return -ENXIO;
 
 	priv = mgr->priv;
···
 	const struct zynqmp_eemi_ops *eemi_ops = zynqmp_pm_get_eemi_ops();
 	u32 status;
 
-	if (!eemi_ops || !eemi_ops->fpga_get_status)
+	if (IS_ERR_OR_NULL(eemi_ops) || !eemi_ops->fpga_get_status)
 		return FPGA_MGR_STATE_UNKNOWN;
 
 	eemi_ops->fpga_get_status(&status);