x86/Sandy Bridge: Sandy Bridge workaround depends on CONFIG_PCI

commit e43b3cec711a61edf047adf6204d542f3a659ef8 upstream.

early_pci_allowed() and read_pci_config_16() are only available if
CONFIG_PCI is defined.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Abdallah Chatila <abdallah.chatila@ericsson.com>