block: Fix bdrv_aligned_p*v() for qiov_offset != 0

block: Fix bdrv_aligned_p*v() for qiov_offset != 0

Since these functions take a @qiov_offset, they must always take it into
account when working with @qiov.  There are a couple of places where
they do not, but they should.

Fixes: 65cd4424b9df03bb5195351c33e04cbbecc0705c
       ("block/io: bdrv_aligned_preadv: use and support qiov_offset")
Fixes: 28c4da28695bdbe04b336b2c9c463876cc3aaa6d
       ("block/io: bdrv_aligned_pwritev: use and support qiov_offset")
Reported-by: Claudio Fontana <cfontana@suse.de>
Reported-by: Bruce Rogers <brogers@suse.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200728120806.265916-2-mreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Tested-by: Claudio Fontana <cfontana@suse.de>
Tested-by: Bruce Rogers <brogers@suse.com>