sparc64: add reads{b,w,l}/writes{b,w,l}

Some drivers need these for compile-testing. On most architectures
they come from asm-generic/io.h, but not on sparc64, which has its
own definitions.

Since we already have ioread*_rep()/iowrite*_rep() that have the
same behavior on sparc64 (i.e. all PCI I/O space is memory mapped),
we can rename the existing helpers and add macros to define them
to the same implementation.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David S. Miller <davem@davemloft.net>
Tested-by: Boris Brezillon <boris.brezillon@bootlin>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>