nouveau: fix acpi_lid_open undefined

When CONFIG_ACPI_BUTTON=m (and probably when ACPI_BUTTON is not enabled)
and NOUVEAU is built-in (not as a loadable module):

nouveau_connector.c:(.text+0xe17ce): undefined reference to `acpi_lid_open'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>