sparc64: avoid code duplication in io_64.h

Several of the small IO functions ended up having the same implementation.
Use __raw_{read,write}* + {read,write}* as base for the others.

Continue to use static inline functions to get full type check.
The size of vmlinux for a defconfig build was the same when
using static inline and macros for the functions - so there
was no size win when using macros.

This was tested with gcc 4.8.2 + binutils 2.24.
For such simple constructs I assume older gcc's will
do the same job.

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