sbitmap: remove stale comment in sbq_calc_wake_batch

	unsigned int shallow_depth;

	/*

	 * For each batch, we wake up one queue. We need to make sure that our

	 * batch size is small enough that the full depth of the bitmap,

	 * potentially limited by a shallow depth, is enough to wake up all of

	 * the queues.

	 *

	 * Each full word of the bitmap has bits_per_word bits, and there might

	 * be a partial word. There are depth / bits_per_word full words and

	 * depth % bits_per_word bits left over. In bitwise arithmetic: