[prim] Packer to remove unused parameter.
[prim] Packer to remove unused parameter.

Old packer used MaxW to create internal storage. Newer version does not
use MaxW paramter. Removed it.

Signed-off-by: Eunchan Kim <cb7bc7ceb22698f298c67faa994fd9ddf3cab298@opentitan.org>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan