ruby: slicc: replace max_in_port_rank with number of inports

ruby: slicc: replace max_in_port_rank with number of inports

This patch replaces max_in_port_rank with the number of inports.  The use of
max_in_port_rank was causing spurious re-builds and incorrect initialization
of variables in ruby related regression tests.  This was due to the variable
value being used across threads while compiling when it was not meant to be.

Since the number of inports is state machine specific value, this problem
should get solved.