block: move lower_48_bits() to block

The function is not generally applicable enough to be included in the core
kernel header. Move it to block since it's the only subsystem using it.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20220327173316.315-1-kbusch@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

include/linux/kernel.h

@@ -63,15 +63,6 @@
 }					\
 )
 
-/**
- * lower_48_bits() - return bits 0-47 of a number
- * @n: the number we're accessing
- */
-static inline u64 lower_48_bits(u64 n)
-{
-	return n & ((1ull << 48) - 1);
-}
-
 /**
  * upper_32_bits - return bits 32-63 of a number
  * @n: the number we're accessing

include/linux/t10-pi.h

@@ -59,6 +59,15 @@ struct crc64_pi_tuple {
 	__u8   ref_tag[6];
 };
 
+/**
+ * lower_48_bits() - return bits 0-47 of a number
+ * @n: the number we're accessing
+ */
+static inline u64 lower_48_bits(u64 n)
+{
+	return n & ((1ull << 48) - 1);
+}
+
 static inline u64 ext_pi_ref_tag(struct request *rq)
 {
 	unsigned int shift = ilog2(queue_logical_block_size(rq->q));