mem: Change accessor function names to match the port interface

mem: Change accessor function names to match the port interface

This patch changes the names of the cache accessor functions to be in
line with those used by the ports. This is done to avoid confusion and
get closer to a one-to-one correspondence between the interface of the
memory object (the cache in this case) and the port itself.

The member function timingAccess has been split into a snoop/non-snoop
part to avoid branching on the isResponse() of the packet.