tb_invalidate_page_range() was intended to be used to invalidate an
area of a TB which the guest explicitly flushes from i-cache. However,
QEMU detects writes to code areas where TBs have been generated, so
his has never been useful.

Delete the function, adjust callers.
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>