stmmac: pci: add MSI support for Intel Quark X1000

In Intel Quark SoC X1000, both of the Ethernet controllers support
MSI interrupt handling. This patch enables them to use MSI interrupt
servicing in stmmac_pci for Intel Quark X1000.

Signed-off-by: Kweh, Hock Leong <hock.leong.kweh@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>