[SPARC64]: small Makefile cleanups

A few trivial Makefile cleanups
- dependencipes in head.o was all wrong - deleted
- CMODEL_CFLAG was not used anywhere
- NEW_GCC was then not used outside sparc64/Makefe - do not export it
- FIXME seems not appropriate - all other put oprofile in drivers-y too
- No reason to do -I. (and it still builds)

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>