cxl/acpi: Ensure ports ready at cxl_acpi_probe() return

In order to ensure root CXL ports are enabled upon cxl_acpi_probe()
when the 'cxl_port' driver is built as a module, arrange for the
module to be pre-loaded or built-in.

The "Fixes:" but no "Cc: stable" on this patch reflects that the issue
is merely by inspection since the bug that triggered the discovery of
this potential problem [1] is fixed by other means. However, a stable
backport should do no harm.

Fixes: 8dd2bc0 ("cxl/mem: Add the cxl_mem driver")
Link: http://lore.kernel.org/[email protected] [1]
Signed-off-by: Dan Williams <[email protected]>
Tested-by: Gregory Price <[email protected]>
Reviewed-by: Jonathan Cameron <[email protected]>
Reviewed-by: Ira Weiny <[email protected]>
Link: https://patch.msgid.link/172964781969.81806.17276352414854540808.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Ira Weiny <[email protected]>

drivers/cxl/acpi.c

@@ -924,6 +924,13 @@ static void __exit cxl_acpi_exit(void)
 
 /* load before dax_hmem sees 'Soft Reserved' CXL ranges */
 subsys_initcall(cxl_acpi_init);
+
+/*
+ * Arrange for host-bridge ports to be active synchronous with
+ * cxl_acpi_probe() exit.
+ */
+MODULE_SOFTDEP("pre: cxl_port");
+
 module_exit(cxl_acpi_exit);
 MODULE_DESCRIPTION("CXL ACPI: Platform Support");
 MODULE_LICENSE("GPL v2");