CHROMIUM: r8169.c: Re-enable MSI to fix D3 wake for RTL8111e.

CHROMIUM: r8169.c: Re-enable MSI to fix D3 wake for RTL8111e.

In 3.0, kernel function, rtl_try_msi, unconditionally wrote config2
(0x53) register regardless of device version.

In 3.2, this write was made conditional based off dialog found in
https://lkml.org/lkml/2011/12/14/19.  That dialog states that MSI is
only supported for r8169 series devices.  Datasheets I have state MSI
support is available for the RTL81111e device I'm testing.
Additionally, I'm able to see the correct reporting of the MSI by
interrogating the PMCSR and /proc/interrupts.

This temporary patch returns the driver to its 3.0 functionality of
unconditionally writing config2 register while I begin a dialog with
maintainer/vendor to resolve the larger issue.

BUG=chromium-os:27991
TEST=manual
1. boot kernel w/o LAN connected and goto shell.
2. lspci -vvv -s 02:0 | grep "Status: D"
  Status: D3 NoSoftRst+ PME-Enable+ DSel=0 DScale=0 PME-
3. connect LAN and repeat 2.
  Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-

Change-Id: Ifbef2a63ab68a25954910a613ccc9def542fe612
Signed-off-by: Todd Broch <tbroch@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/19399
Reviewed-by: Sameer Nanda <snanda@chromium.org>