dm: fix double RCU unlock in dm_dax_zero_page_range() error path

Remove redundant dm_put_live_table() in dm_dax_zero_page_range() error
path to fix sparse warning:
drivers/md/dm.c:1208:9: warning: context imbalance in 'dm_dax_zero_page_range' - unexpected unlock

Fixes: cdf6cdcd ("dm,dax: Add dax zero_page_range operation")
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>