stmmac: intel: Simplify intel_eth_pci_remove()

There is no point to call pcim_iounmap_regions() in the remove function,
this frees a managed resource that would be release by the framework
anyway.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>