BugLink: http://bugs.launchpad.net/bugs/1638700

From v4.3, the incoming bio can be very big[1], and it is
required to split it first in .make_request_fn(), so
we need to do that for hio.c too.

[1] c66a14d0(block: simplify bio_add_page())
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>