tile: remove unused header

Nothing includes memprof.h. Nothing uses the macros it defines. It seems
it is just a remnant of the proposed memprof functionality, which got
dropped before the Tilera architecture got added to the tree. This
header can safely be removed.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>