early_me_native.c: Remove unused pci_write_dword_ptr.

Change-Id: I97f4ef373c250665c4a2265571e71a27ecef13da
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: http://review.coreboot.org/7680
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>