vfio/spapr: Move VFIO_CHECK_EXTENSION into tce_iommu_ioctl()

The PPC64 kconfig is a bit of a rats nest, but it turns out that if
CONFIG_SPAPR_TCE_IOMMU is on then EEH must be too:

config SPAPR_TCE_IOMMU
	bool "sPAPR TCE IOMMU Support"
	depends on PPC_POWERNV || PPC_PSERIES
	select IOMMU_API
	help
	  Enables bits of IOMMU API required by VFIO. The iommu_ops
	  is not implemented as it is not necessary for VFIO.

config PPC_POWERNV
	select FORCE_PCI

config PPC_PSERIES
	select FORCE_PCI

config EEH
	bool
	depends on (PPC_POWERNV || PPC_PSERIES) && PCI
	default y

So, just open code the call to eeh_enabled() into tce_iommu_ioctl().
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/2-v5-fc5346cacfd4+4c482-vfio_modules_jgg@nvidia.comSigned-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/vfio_iommu_spapr_tce.c

@@ -785,14 +785,12 @@ static long tce_iommu_ioctl(void *iommu_data,
 		switch (arg) {
 		case VFIO_SPAPR_TCE_IOMMU:
 		case VFIO_SPAPR_TCE_v2_IOMMU:
-			ret = 1;
-			break;
+			return 1;
+		case VFIO_EEH:
+			return eeh_enabled();
 		default:
-			ret = vfio_spapr_iommu_eeh_ioctl(NULL, cmd, arg);
-			break;
+			return 0;
 		}
-
-		return (ret < 0) ? 0 : ret;
 	}
 
 	/*

drivers/vfio/vfio_spapr_eeh.c

@@ -24,12 +24,6 @@ long vfio_spapr_iommu_eeh_ioctl(struct iommu_group *group,
 	long ret = -EINVAL;
 
 	switch (cmd) {
-	case VFIO_CHECK_EXTENSION:
-		if (arg == VFIO_EEH)
-			ret = eeh_enabled() ? 1 : 0;
-		else
-			ret = 0;
-		break;
 	case VFIO_EEH_PE_OP:
 		pe = eeh_iommu_group_to_pe(group);
 		if (!pe)