bcache: use routines from lib/crc64.c for CRC64 calculation

Now we have crc64 calculation in lib/crc64.c, it is unnecessary for
bcache to use its own version.  This patch changes bcache code to use
crc64 routines in lib/crc64.c.

Link: http://lkml.kernel.org/r/20180718165545.1622-3-colyli@suse.de


Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Michael Lyle <mlyle@lyle.org>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Noah Massey <noah.massey@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>