sparc32: clean up io_32.h

After introducing asm-generic/io.h a few things could still be cleaned up
o Drop useless macro indirection for sbus_* io access methods
  They were in the past used to hide casts between long and pointers
  but this is no longer so
o Fix function definitions for sbus memory functions so
  return value appear on same line as function name

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