generic/204: remove unnecessary _scratch_mkfs call

generic/204: remove unnecessary _scratch_mkfs call

The test case generic/204 calls _scratch_mkfs to get data block size and
i-node size of the filesystem and obtained data block size is passed to
the following _scratch_mfks_sized call as an option. However, the
_scratch_mkfs call is unnecessary since the sizes can be obtained by
_scratch_mkfs_sized call without the data block size option.

Also the _scratch_mkfs call is harmful when the _scratch_mkfs succeeds
and the _scratch_mkfs_sized fails. In this case, the _scratch_mkfs
leaves valid working filesystem on scratch device then following mount
and IO operations can not detect the failure of _scratch_mkfs_sized.
This results in the test case run with unexpected test condition.

Hence, remove the _scratch_mkfs call and the data block size option for
_scratch_mkfs_sized call.

Suggested-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>