testing: nvdimm: Add MODULE_DESCRIPTION() macros

When building with W=1 the following errors are seen:

WARNING: modpost: missing MODULE_DESCRIPTION() in tools/testing/nvdimm/test/nfit_test.o
WARNING: modpost: missing MODULE_DESCRIPTION() in tools/testing/nvdimm/test/ndtest.o

Add the required MODULE_DESCRIPTION() to the test platform device
drivers.

Suggested-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Reviewed-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Link: https://patch.msgid.link/r/20240611-nvdimm-test-mod-warn-v1-1-4a583be68c17@intel.com


Signed-off-by: Ira Weiny <ira.weiny@intel.com>