ANDROID: block: Add support for filesystem requests and small segments

Add support in the bio splitting code and also in the bio submission code
for bios with segments smaller than the page size.

Bug: 308663717
Bug: 319125789
Change-Id: I056659cf86c04fb095aa01cd3d274d29417782ac
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[jyescas@google.com: Call blk_segments() in blk_mq_submit_bio()
                     for the case when request is defined or it
                     is null]
Signed-off-by: Juan Yescas <jyescas@google.com>