ANDROID: block: Support submitting passthrough requests with small segments

If the segment size is smaller than the page size there may be multiple
segments per bvec even if a bvec only contains a single page. Hence this
patch.

Bug: 308663717
Bug: 319125789
Change-Id: I446aab83a2c519cb3c42d5d8ffd814dcc34274d2
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Juan Yescas <jyescas@google.com>