qcow2: Fix alignment checks in encrypted images

qcow2: Fix alignment checks in encrypted images

I/O requests to encrypted media should be aligned to the sector size
used by the underlying encryption method, not to BDRV_SECTOR_SIZE.
Fortunately this doesn't break anything at the moment because
both existing QCRYPTO_BLOCK_*_SECTOR_SIZE have the same value as
BDRV_SECTOR_SIZE.

The checks in qcow2_co_preadv_encrypted() are also unnecessary because
they are repeated immediately afterwards in qcow2_co_encdec().

Signed-off-by: Alberto Garcia <[email protected]>
Message-Id: <20200213171646[email protected]>
Reviewed-by: Daniel P. Berrangé <[email protected]>
Signed-off-by: Kevin Wolf <[email protected]>