updater: Remove some redundant arguments.

Clean up a few functions that take CommandParameters& as the first
parameter. We don't need to take duplicate arguments if they always come
from CommandParameters. This redundancy came from the point we replaced
strtok()s (commit baad2d45).

Test: Apply an incremental update with the new updater.
Change-Id: I2912b8ce6bc7580bf7f566e125f12270e679e155