powernv/pci: Use pnv_phb as the private data for debugfs entries

Use the pnv_phb structure as the private data pointer for the debugfs
files.  This lets us delete some code and an open-coded use of
hose->private_data.
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190912052945.12589-1-oohall@gmail.com

arch/powerpc/platforms/powernv/pci-ioda.c

@@ -3090,19 +3090,12 @@ static void pnv_ioda_setup_pe_seg(struct pnv_ioda_pe *pe)
 #ifdef CONFIG_DEBUG_FS
 static int pnv_pci_diag_data_set(void *data, u64 val)
 {
-	struct pci_controller *hose;
-	struct pnv_phb *phb;
+	struct pnv_phb *phb = data;
 	s64 ret;
 
 	if (val != 1ULL)
 		return -EINVAL;
 
-	hose = (struct pci_controller *)data;
-	if (!hose || !hose->private_data)
-		return -ENODEV;
-
-	phb = hose->private_data;
-
 	/* Retrieve the diag data from firmware */
 	ret = opal_pci_get_phb_diag_data2(phb->opal_id, phb->diag_data,
 					  phb->diag_data_size);
@@ -3141,7 +3134,7 @@ static void pnv_pci_ioda_create_dbgfs(void)
 		}
 
 		debugfs_create_file_unsafe("dump_diag_regs", 0200, phb->dbgfs,
-					   hose, &pnv_pci_diag_data_fops);
+					   phb, &pnv_pci_diag_data_fops);
 	}
 #endif /* CONFIG_DEBUG_FS */
 }