bcache: Kill sequential_merge option

It never really made sense to expose this, so just kill it.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

diff --cc drivers/md/bcache/bcache.h
Simple merge

diff --cc drivers/md/bcache/request.c
Simple merge

diff --cc drivers/md/bcache/super.c
Simple merge

diff --cc drivers/md/bcache/sysfs.c
Simple merge