cxl/acpi: Fix CXL_ACPI and CXL_PMEM Kconfig tristate mismatch

cxl/acpi: Fix CXL_ACPI and CXL_PMEM Kconfig tristate mismatch

commit 93d0fcdddc9e7be9d4f42acbe57bc90dbb0fe75d upstream.

Commit e7e222ad73d9 ("cxl: Move devm_cxl_add_nvdimm_bridge() to
cxl_pmem.ko") moves devm_cxl_add_nvdimm_bridge() into the cxl_pmem file,
which has independent config compile options for built-in or module. The
call from cxl_acpi_probe() is guarded by IS_ENABLED(CONFIG_CXL_PMEM),
which evaluates to true for both =y and =m.

When CONFIG_CXL_PMEM=m, a built-in cxl_acpi attempts to reference a
symbol exported by a module, which fails to link. CXL_PMEM cannot simply
be promoted to =y in this configuration because it depends on LIBNVDIMM,
which may itself be =m.

Add a Kconfig dependency to prevent CXL_ACPI from being built-in when
CXL_PMEM is a module. This contrains CXL_ACPI to =m when CXL_PMEM=m,
while still allowing CXL_ACPI to be freely configured when CXL_PMEM is
either built-in or disabled.

[ dj: Fix up commit reference formatting. ]

Fixes: e7e222ad73d9 ("cxl: Move devm_cxl_add_nvdimm_bridge() to cxl_pmem.ko")
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://patch.msgid.link/20260305204057.1516948-1-kbusch@meta.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>