bitmap: Align documentation between bitmap_gather() and bitmap_scatter()

The bitmap_scatter() mistakenly refers to itself for detailed explanation
about the relationships of two. Instead of simply fixing this, align text
in both making a cross-reference.

Fixes: de5f84338970 ("lib/bitmap: Introduce bitmap_scatter() and bitmap_gather() helpers")
Signed-off-by: Andy Shevchenko <[e-mail]>
Signed-off-by: Yury Norov <[e-mail]>

include/linux/bitmap.h

···
  *	      ...0..11...0..10
  *	dst:  0000001100000010
  *
- * A relationship exists between bitmap_scatter() and bitmap_gather().
+ * A relationship exists between bitmap_scatter() and bitmap_gather(). See
+ * bitmap_gather() for the bitmap gather detailed operations. TL;DR:
  * bitmap_gather() can be seen as the 'reverse' bitmap_scatter() operation.
- * See bitmap_scatter() for details related to this relationship.
  */
 static __always_inline
 void bitmap_scatter(unsigned long *dst, const unsigned long *src,
···
  *	dst:  0000000000011010
  *
  * A relationship exists between bitmap_gather() and bitmap_scatter(). See
- * bitmap_scatter() for the bitmap scatter detailed operations.
+ * bitmap_scatter() for the bitmap scatter detailed operations. TL;DR:
+ * bitmap_scatter() can be seen as the 'reverse' bitmap_gather() operation.
+ *
  * Suppose scattered computed using bitmap_scatter(scattered, src, mask, n).
  * The operation bitmap_gather(result, scattered, mask, n) leads to a result
  * equal or equivalent to src.