include/bcd: move bcd code to commonlib/bsd/include

Move bcd2bin() / bin2bcd() functions to commonlib/bsd/include/

Also, the license is changed from GPL to BSD.
This is because it is needed from "utils" (see CL in the chain).

For reference bin2bcd() & bcd2bin() are very simple functions.
There are already BSD implementations, like these ones (just to
name a few):
https://chromium.googlesource.com/chromiumos/platform/mosys/+/refs/heads/main/include/lib/math.h#67
http://web.mit.edu/freebsd/head/sys/contrib/octeon-sdk/cvmx-cn3010-evb-hs5.c

BUG=b:172210863
TEST=make (everything compiled Ok).

Change-Id: If2eba82da35838799bcbcf38303de6bd53f7eb72
Signed-off-by: Ricardo Quesada <ricardoq@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56904
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/drivers/elog/elog.c

@@ -1,10 +1,10 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
 #include <acpi/acpi.h>
-#include <bcd.h>
 #include <boot_device.h>
 #include <bootstate.h>
 #include <cbmem.h>
+#include <commonlib/bsd/bcd.h>
 #include <commonlib/bsd/elog.h>
 #include <commonlib/region.h>
 #include <console/console.h>