f2fs: ensure only power of 2 zone sizes are allowed

F2FS zoned support has power of 2 zone size assumption in many places
such as in __f2fs_issue_discard_zone, init_blkz_info. As the power of 2
requirement has been removed from the block layer, explicitly add a
condition in f2fs to allow only power of 2 zone size devices.

This condition will be relaxed once those calculation based on power of
2 is made generic.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>