Add address_width and register count to C-Header Generator

[ghost]

Since we use the registers on an AXI-Bus, we would like to check the legality of register reads/writes by checking whether some given address lies within the generated register range.

Taken from the current generator, it would look something like this:

#define {{ module_prefix()|upper }}_ADDR_WIDTH {{ "0x%x" % (address_width) }}
#define {{ module_prefix()|upper }}_REG_COUNT {{ (register_count) }}

@esynr3z Does it make sense to open a pull request and implement it into "V1" or should I wait for the release of V2 and do it then?