Specify the lua and zstd license text in the manor in which the
kernel MODULE_LICENSE macro requires it. The now duplicate entries
were merged and a comment added to make it clear what they apply to.
Reviewed-by: Christian Schwarz <christian.schwarz@nutanix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#13641