asm-generic: io: Fix ioread16/32be and iowrite16/32be

Fix ioreadXXbe and iowriteXXbe functions which did
additional little endian conversion on native big endian systems.
Using be_to_cpu (cpu_to_be) conversions with __raw_read/write
functions have resolved it.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Will Deacon <will.deacon@arm.com>
CC: linux-arch@vger.kernel.org