ixgbe: cleanup ixgbe_init_mbx_params_pf namespace issue

The function ixgbe_init_mbx_params_pf isn't used unless CONFIG_PCI_IOV
is defined.  This is causing namespace warnings.  So I wrapped its
definition in CONFIG_PCI_IOV too.

Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Tested-by: Stephen Ko <stephen.s.ko@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ixgbe/ixgbe_mbx.c b/drivers/net/ixgbe/ixgbe_mbx.c
index ea82c5a..f215c4c 100644
--- a/drivers/net/ixgbe/ixgbe_mbx.c
+++ b/drivers/net/ixgbe/ixgbe_mbx.c
@@ -437,6 +437,7 @@
 	return ret_val;
 }
 
+#ifdef CONFIG_PCI_IOV
 /**
  *  ixgbe_init_mbx_params_pf - set initial values for pf mailbox
  *  @hw: pointer to the HW structure
@@ -465,6 +466,7 @@
 		break;
 	}
 }
+#endif /* CONFIG_PCI_IOV */
 
 struct ixgbe_mbx_operations mbx_ops_generic = {
 	.read                   = ixgbe_read_mbx_pf,