lib: bitmap: yet another simplification in __bitmap_shift_right

If left is 0, we can just let mask be ~0UL, so that anding with it is a
no-op.  Conveniently, BITMAP_LAST_WORD_MASK provides precisely what we
need, and we can eliminate left.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/bitmap.c

@@ -113,9 +113,9 @@ EXPORT_SYMBOL(__bitmap_complement);
 void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
 			unsigned shift, unsigned nbits)
 {
-	unsigned k, lim = BITS_TO_LONGS(nbits), left = nbits % BITS_PER_LONG;
+	unsigned k, lim = BITS_TO_LONGS(nbits);
 	unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
-	unsigned long mask = (1UL << left) - 1;
+	unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
 	for (k = 0; off + k < lim; ++k) {
 		unsigned long upper, lower;
 
@@ -127,12 +127,12 @@ void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
 			upper = 0;
 		else {
 			upper = src[off + k + 1];
-			if (off + k + 1 == lim - 1 && left)
+			if (off + k + 1 == lim - 1)
 				upper &= mask;
 			upper <<= (BITS_PER_LONG - rem);
 		}
 		lower = src[off + k];
-		if (left && off + k == lim - 1)
+		if (off + k == lim - 1)
 			lower &= mask;
 		lower >>= rem;
 		dst[k] = lower | upper;