[SPARC64]: Fix two year old bug in early bootup asm.

We try to fetch the CIF entry pointer from %o4, but that
can get clobbered by the early OBP calls.  It is saved
in %l7 already, so actually this "mov %o4, %l7" can just
be completely removed with no other changes.

Signed-off-by: David S. Miller <davem@davemloft.net>