blk-wbt: remove wbt_track stub

blk-wbt: remove wbt_track stub

cppcheck returns this warning
[block/blk-wbt.h:104] -> [block/blk-wbt.c:592]:
  (warning) Function 'wbt_track' argument order different:
  declaration 'rq, flags, ' definition 'rqos, rq, bio'

In commit 7ca0545cdfbc ("block: remove external dependency on wbt_flags")
wbt_track was removed for the real declaration, its stub should
have been as well.

Signed-off-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20220331185458.3427454-1-trix@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>