generic/{171,172,173,174}: check _scratch_mkfs_sized return code

generic/{171,172,173,174}: check _scratch_mkfs_sized return code

The test cases generic/{171,172,173,174} call _scratch_mkfs before
_scratch_mkfs_sized, and they do not check return code of
_scratch_mkfs_sized. Even if _scratch_mkfs_sized failed, _scratch_mount
after it cannot detect the sized mkfs failure because _scratch_mkfs
already created a file system on the device. This results in unexpected
test condition of the test cases.

To avoid the unexpected test condition, check return code of
_scratch_mkfs_sized in the test cases.

Suggested-by: Naohiro Aota <naohiro.aota@wdc.com>
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>