[SPARC]: Fix mxcc warning

Peter Jones uncovered this one while we were debugging the framebuffer
issues. There are some references to -1 in the mxcc asm code, which
should be 0xffffffff.

This patch gets rid of the -1s.

Signed-off-by: Tom 'spot' Callaway <tcallawa@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>