Extract the crc32 test code into its own source file, to allow to
compile it either to a loadable module, or builtin into the kernel.

Link: http://lkml.kernel.org/r/1483470276-10517-1-git-send-email-geert@linux-m68k.orgSigned-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>