lib/test_bitmap: correct test data offsets for 32-bit

On 32-bit platform the size of long is only 32 bits which makes wrong
offset in the array of 64 bit size.

Calculate offset based on BITS_PER_LONG.

Link: http://lkml.kernel.org/r/20200109103601.45929-1-andriy.shevchenko@linux.intel.com
Fixes: 30544ed5

 ("lib/bitmap: introduce bitmap_replace() helper")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Yury Norov <yury.norov@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>