Dynamically compute number of L1 client channels

Until now, the number of L1 client channels was set statically in the
configuration. This static configuration also assumed the same number of
cached and uncached channels per tile. As we plan to move towards
heterogenous multicore systems, this restriction should be removed.

This commit changes the generator so that number of channels per tile
can be independently set (using cde.Parameters.alterPartial).
The OuterMemorySystem will dynamically compute the number of cached and
uncached channels by summing the number of each kind of channel per core.