nvdimm: fix inline function return type warning
nvdimm: fix inline function return type warning

Fix multiple build warnings when CONFIG_BTT is not enabled:

In file included from ../drivers/nvdimm/bus.c:29:0:
../drivers/nvdimm/nd.h:169:15: warning: return type defaults to 'int' [-Wreturn-type]
 static inline nd_btt_probe(struct nd_namespace_common *ndns, void *drvdata)
               ^

Signed-off-by: Randy Dunlap <6f29df8e90a57f1ba61ffd63b0468c86bb6d3a99@infradead.org>
Cc: Dan Williams <24ee2bf0bd8ac766c348bf1f0639943bac1535c6@intel.com>
Cc: 98172d8e42f0f3d6eba161b036af0414bd3ef6f5@lists.01.org
Signed-off-by: Dan Williams <24ee2bf0bd8ac766c348bf1f0639943bac1535c6@intel.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs