nfs: cleanup tracepoint declarations

Cleanup tracepoint declarations by replacing commas with
semicolons to better match other tracepoint declarations.

No functional changes introduced.

Signed-off-by: Leo Martins <loemra.dev@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>