tcg: move locking for tb_invalidate_phys_page_range up

In the linux-user case all things that involve ''l1_map' and PageDesc
tweaks are protected by the memory lock (mmpa_lock). For SoftMMU mode
we previously relied on single threaded behaviour, with MTTCG we now use
the tb_lock().

As a result we need to do a little re-factoring  and push the taking of
this lock up the call tree. This requires a slightly different entry for
the SoftMMU and user-mode cases from tb_invalidate_phys_range.

This also means user-mode breakpoint insertion needs to take two locks
but it hadn't taken any previously so this is an improvement.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20161027151030.20863-20-alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
