trace/events/block.h: drop kernel-doc for dropped function parameter

Fix kernel-doc warning: the parameter was removed, so also remove
the kernel-doc notation for it.

../include/trace/events/block.h:278: warning: Excess function parameter 'error' description in 'trace_block_bio_complete'

Fixes: d24de76a

 ("block: remove the error argument to the block_bio_complete tracepoint")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>