lslocks: make SIZE filterable by normalizing to bytes

lslocks: make SIZE filterable by normalizing to bytes

The SIZE column may be printed in raw bytes or human-readable
units (KB/MB, etc.), which makes number-based comparison impossible.

Normalize SIZE to a byte value and store it in the cell via
libsmartcols `scols_cell_set_userdata`. When evaluating filter
expressions, use the stored byte value instead of the printed SIZE.

This enables consistent numeric comparisons (e.g., -Q 'SIZE > 1M')
regardless of the output format.

No change to printed output.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>