_scratch_mkfs_geom(): Filter out 'k' suffix from fs block size

_scratch_mkfs_geom(): Filter out 'k' suffix from fs block size

If the original value of $MKFS_OPTIONS contained a block size value
having 'k' as a suffix (e.g. -b size=4k), then the newly constructed
value of $MKFS_OPTIONS will have 'k' suffixed to the value of
$blocksize.  $blocksize itself is specified in units of bytes. Hence
having 'k' suffixed to this value will result in an incorrect block
size.

This commit fixes the bug by conditionally filtering out the 'k'
suffix from block size option present in the original value of
$MKFS_OPTIONS.

Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>