ANDROID: dm-bow: avoid truncating the logical block size

Upstream commit ad6bf88a ("block: fix an integer overflow in logical
block size") changed queue_limits::logical_block_size from 'unsigned
short' to 'unsigned int', and this commit has been backported to the LTS
branches.  Update the computation in dm_bow_io_hints() to match.

This mirrors upstream commit 64611a15 ("dm crypt: avoid truncating
the logical block size") which fixed the same bug in dm-crypt.

Fixes: 7df64f62 ("ANDROID: dm-bow: Add block_size option")
Change-Id: I45eba7d21cf178e4b8e624ef5f819a1ffb015a8d
Signed-off-by: Eric Biggers <ebiggers@google.com>