lib: merge CRC16-CCITT into u-boot/crc.h

This merges the CRC16-CCITT headers into u-boot/crc.h to prepare for
rolling CRC16 into the hash infrastructure.  Given that CRC8, CRC32
and CRC32-C already have their prototypes in a single header file, it
seems a good idea to also include CRC16-CCITT in the same.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff --git a/lib/crc16.c b/lib/crc16.c
index 763ae33..25bdfd8 100644
--- a/lib/crc16.c
+++ b/lib/crc16.c
@@ -22,7 +22,7 @@
  *==========================================================================
  */
 
-#include "crc.h"
+#include <u-boot/crc.h>
 
 /* Table of CRC constants - implements x^16+x^12+x^5+1 */
 static const uint16_t crc16_tab[] = {