nvdimm/btt: fix btt_blk_cleanup() kernel-doc

Correct the function parameters to prevent kernel-doc warnings:

btt.c:1567: warning: Function parameter or member 'nd_region' not described in 'btt_init'
btt.c:1567: warning: Excess function parameter 'maxlane' description in 'btt_init'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc:  <nvdimm@lists.linux.dev>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20231207210545.24056-1-rdunlap@infradead.org


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