tile: remove HUGE_VMAP dead code

tile: remove HUGE_VMAP dead code

A config option to allow a variant vmap() using huge pages that was never
upstreamed had some bits of code related to it scattered around the tile
architecture; the config option was removed downstream and this commit
cleans up the scattered evidence of it from the upstream as well.

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