cris: use generic io.h

fixes the warning:

lib/iomap.c: In function ‘ioread8_rep’:
./arch/cris/include/asm/io.h:139:31: warning: statement with no effect [-Wunused-value]
 #define insb(port,addr,count) (cris_iops ? cris_iops->read_io(port,addr,1,count) : 0)
                               ^
lib/iomap.c:56:3: note: in definition of macro ‘IO_COND’
   is_pio;      \
   ^
lib/iomap.c:197:16: note: in expansion of macro ‘insb’
  IO_COND(addr, insb(port,dst,count), mmio_insb(addr, dst, count));
                ^

cris_iops was previously set to NULL (no matter if CONFIG_PCI was set or
not), but was removed in commit ab28e96f ("CRIS v32: remove old GPIO
and LEDs code"). Before commit ab28e96f ("CRIS v32: remove old GPIO
and LEDs code"), cris_iops could have been set from an external module,
since it was exported, but as commit c24bf9b4 ("CRIS: fix I/O
macros") noted, the macros using cris_iops have been broken since first
included, so they could never have worked.

Because of this, instead of readding cris_iops, remove all special
handling of cris_iops. By doing so, we can rely on the default
implementation of almost all functions previously defined in our arch
specific io.h.

Signed-off-by: Niklas Cassel <nks@flawful.org>
Signed-off-by: Jesper Nilsson <jespern@axis.com>