cxl/Kconfig: Default drivers to CONFIG_CXL_BUS

CONFIG_CXL_BUS is default 'n' as expected for new functionality. When
that is enabled do not make the end user hunt for all the expected
sub-options to enable. For example CONFIG_CXL_BUS without CONFIG_CXL_MEM
is an odd/expert configuration, so is CONFIG_CXL_MEM without
CONFIG_CXL_ACPI (on ACPI capable platforms). Default CONFIG_CXL_MEM and
CONFIG_CXL_ACPI to CONFIG_CXL_BUS.

Acked-by: Ben Widawsky <ben.widawsky@intel.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/162325450105.2293126.17046356425194082921.stgit@dwillia2-desk3.amr.corp.intel.com


Signed-off-by: Dan Williams <dan.j.williams@intel.com>