net: e1000e & ixgbe: Remove PCI_HEADER_TYPE_MFD duplicates

PCI_HEADER_TYPE_MULTIFUNC is define by e1000e and ixgbe and both are
unused. There is already PCI_HEADER_TYPE_MFD in pci_regs.h anyway which
should be used instead so remove the duplicated defines of it.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Hariprasad Kelam <hkelam@marvell.com>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Acked-by: Sasha Neftin <sasha.neftin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>