tools/testing/nvdimm: add watermarks for dax_pmem* modules

Add nfit_test 'watermarks' for the dax_pmem, dax_pmem_core, and
dax_pmem_compat modules. This causes the nfit_test module to fail
loading in case any of these modules are also not overridden with the
ldconfig wrapped modules. Without this, nfit_test would sometimes fail
creation of device-dax namespaces on the nfit_test_bus with an unhelpful
error log such as:

dax_pmem dax5.0: could not reserve metadata
dax_pmem: probe of dax5.0 failed with error -16

Which was caused due to the unwrapped version of
devm_request_mem_region() being called.

Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

tools/testing/nvdimm: force nfit_test to depend on instrumented modules

The libnvdimm unit tests will fail when they are run against the
production / in-tree version of libnvdimm.ko or nfit.ko due to
symbols not being mocked per nfit_test's expectation. For example,
nfit_test expects acpi_evaluate_dsm() to be replaced by
__wrap_acpi_evaluate_dsm() to test how acpi_nfit_ctl() responds to
different stimuli.

Create a test-only symbol name that nfit_test links against to cause
module load failures when the wrong module is present.

For example, with this change, attempts to use the wrong module will
report:

nfit_test: Unknown symbol libnvdimm_test (err 0)

Reported-by: Dave Jiang <dave.jiang@intel.com>
Reported-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>