x86, efi: correct precedence of operators in setup_efi_pci

With the current code, the condition in the if() doesn't make much sense due to
precedence of operators.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Link: http://lkml.kernel.org/r/1356030701-16284-25-git-send-email-sasha.levin@oracle.com
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>