tools/testing/cxl: Fix cxl_hdm_decode_init() calling convention

This failing signature:

[    8.392669] cxl_bus_probe: cxl_port endpoint2: probe: 970997760
[    8.392670] cxl_port: probe of endpoint2 failed with error 970997760
[    8.392719] create_endpoint: cxl_mem mem0: add: endpoint2
[    8.392721] cxl_mem mem0: endpoint2 failed probe
[    8.392725] cxl_bus_probe: cxl_mem mem0: probe: -6

...shows cxl_hdm_decode_init() resulting in a return code ("970997760")
that looks like stack corruption. The problem goes away if
cxl_hdm_decode_init() is not mocked via __wrap_cxl_hdm_decode_init().

The corruption results from the mismatch that the calling convention for
cxl_hdm_decode_init() is:

int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm)

...and __wrap_cxl_hdm_decode_init() is:

bool __wrap_cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm)

...i.e. an int is expected but __wrap_hdm_decode_init() returns bool.

Fix the convention and cleanup the organization to match
__wrap_cxl_await_media_ready() as the difference was a red herring that
distracted from finding the bug.

Fixes: 92804edb ("cxl/pci: Drop @info argument to cxl_hdm_decode_init()")
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Adam Manzanares <a.manzanares@samsung.com>
Link: https://lore.kernel.org/r/165603870776.551046.8709990108936497723.stgit@dwillia2-xfhSigned-off-by: Dan Williams <dan.j.williams@intel.com>

tools/testing/cxl/test/mock.c

@@ -208,13 +208,15 @@ int __wrap_cxl_await_media_ready(struct cxl_dev_state *cxlds)
 }
 EXPORT_SYMBOL_NS_GPL(__wrap_cxl_await_media_ready, CXL);
 
-bool __wrap_cxl_hdm_decode_init(struct cxl_dev_state *cxlds,
-				struct cxl_hdm *cxlhdm)
+int __wrap_cxl_hdm_decode_init(struct cxl_dev_state *cxlds,
+			       struct cxl_hdm *cxlhdm)
 {
 	int rc = 0, index;
 	struct cxl_mock_ops *ops = get_cxl_mock_ops(&index);
 
-	if (!ops || !ops->is_mock_dev(cxlds->dev))
+	if (ops && ops->is_mock_dev(cxlds->dev))
+		rc = 0;
+	else
 		rc = cxl_hdm_decode_init(cxlds, cxlhdm);
 	put_cxl_mock_ops(index);