The L2CR register contains a number of bits that either impose configuration
which we can't deal with or mean "something is in progress until the bit is
0 again".

Since we don't model the former and we do want to accomodate guests using the
latter semantics, let's just ignore writes to L2CR. That way guests always read
back 0 and are usually happy with that.
Signed-off-by: NAlexander Graf <agraf@suse.de>