arch/tile: enhance existing finv_buffer_remote() routine

It now takes an additional argument so it can be used to
flush-and-invalidate pages that are cached using hash-for-home
as well those that are cached with coherence point on a single cpu.

This allows it to be used more widely for changing the coherence
point of arbitrary pages when necessary.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>