Clarify handling of misaligned load/stores in CVXIF

Created by: vogelpi

It has been agreed to:

• Split misaligned load/stores inside the core always.
• To delay the memory request/response handshake until its clear whether a synchronous exception is triggered or not by that request.
• Keep the memory request signals stable until the handshake as been performed (no retraction of x_mem_valid_i without handshake).