If an interrupt occurs during the fpga_probe routine, the driver
can crash due to an uninitalized PCI drvdata field in intrpt_handler()
This change moves the allocation of the PCI drvdata to the prologue
of the fpga_probe() routine and then relies upon drvdata->id to determine
initialization readiness during the intrpt_handler() routine.
This change moves the allocation of the PCI drvdata to the prologue of the fpga_probe() routine and then relies upon drvdata->id to determine initialization readiness during the intrpt_handler() routine.