bcache: move open brace at end of function definitions to next line

This is not a preferred style to place open brace '{' at the end of
function definition, checkpatch.pl reports error for such coding
style. This patch moves them into the start of the next new line.

Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Shenghui Wang <shhuiw@foxmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>