cris: intmem: fix device_initcall compile warning

Cannot add __init macro to crisv32_intmem_init,
since the function is being called by other functions.
Creating a wrapper instead.

arch/cris/arch-v32/mm/intmem.c: At top level:
arch/cris/arch-v32/mm/intmem.c:148:17: warning: initialization from incompatible pointer type
 device_initcall(crisv32_intmem_init);
                 ^
include/linux/init.h:184:58: note: in definition of macro ‘__define_initcall’
  __attribute__((__section__(".initcall" #id ".init"))) = fn; \

arch/cris/arch-v32/mm/intmem.c:148:1: note: in expansion of macro ‘device_initcall’
 device_initcall(crisv32_intmem_init);
 ^

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