block: introduce bdev_rot()

block: introduce bdev_rot()

Introduce the helper function bdev_rot() to test if a block device is a
rotational one. The existing function bdev_nonrot() which tests for the
opposite condition is redefined using this new helper.
This avoids the double negation (operator and name) that appears when
testing if a block device is a rotational device, thus making the code a
little easier to read.

Call sites of bdev_nonrot() in the block layer are updated to use this
new helper.  Remaining users in other subsystems are left unchanged for
now.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>