i40e: limit debugfs io ops

Don't let the debugfs register read and write commands try to access
outside of the ioremapped space.  While we're at it, remove the use of
a misleading constant.

Change-ID: Ifce2893e232c65c7a76c23532c658f298218a81b
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/i40e/i40e_debugfs.c b/drivers/net/ethernet/intel/i40e/i40e_debugfs.c
index 508efb0..ee96106 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_debugfs.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_debugfs.c
@@ -1495,9 +1495,9 @@
 		}
 
 		/* check the range on address */
-		if (address >= I40E_MAX_REGISTER) {
-			dev_info(&pf->pdev->dev, "read reg address 0x%08x too large\n",
-				 address);
+		if (address > (pf->ioremap_len - sizeof(u32))) {
+			dev_info(&pf->pdev->dev, "read reg address 0x%08x too large, max=0x%08lx\n",
+				 address, (pf->ioremap_len - sizeof(u32)));
 			goto command_write_done;
 		}
 
@@ -1514,9 +1514,9 @@
 		}
 
 		/* check the range on address */
-		if (address >= I40E_MAX_REGISTER) {
-			dev_info(&pf->pdev->dev, "write reg address 0x%08x too large\n",
-				 address);
+		if (address > (pf->ioremap_len - sizeof(u32))) {
+			dev_info(&pf->pdev->dev, "write reg address 0x%08x too large, max=0x%08lx\n",
+				 address, (pf->ioremap_len - sizeof(u32)));
 			goto command_write_done;
 		}
 		wr32(&pf->hw, address, value);