Add probe_expr_width() for specparam value.
Add probe_expr_width() for specparam value.

This patch adds a call to probe_expr_width() before a specparam
value is evaluated. This calculates the expression type/width.

themperek/iverilog,CastMi/iverilog,CastMi/iverilog,themperek/iverilog,CastMi/iverilog,themperek/iverilog