stmmac: intel: use managed PCI function on probe and resume

Update dwmac-intel to use managed function, i.e. pcim_enable_device().

This will allow devres framework to call resource free function for us.

Signed-off-by: Wong Vee Khee <vee.khee.wong@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>