genrams: when pre-loading a RAM with an init file, assert that the file size is not bigger than the size of the memory it is written to

genrams: when pre-loading a RAM with an init file, assert that the file size is not bigger than the size of the memory it is written to

The previous implementation was introducing latches to the GN4124 core under Xilinx ISE.

Tested and verified to work with the following SPEC-based reference designs:
 - WR
 - MT
 - WRTD