By default ARM TF is built with the '-pedantic' compiler flag, which
helps detecting violations of the C standard. However, the mbed TLS
library and its associated authentication module in TF used to fail
building with this compiler flag. As a workaround, the mbed TLS
authentication module makefile used to set the 'DISABLE_PEDANTIC'
TF build flag.

The compiler errors flagged by '-pedantic' in the mbed TLS library
have been fixed between versions 1.3.9 and 2.2.0 and the library now
properly builds with this compiler flag.

This patch fixes the remaining compiler errors in the mbed TLS
authentication module in TF and unsets the 'DISABLE_PEDANTIC' TF
build flag. This means that TF is now always built with '-pedantic'.

In particular, this patch:

 * Removes the final semi-colon in REGISTER_COT() macro.

   This semi-colon was causing the following error message:

   drivers/auth/tbbr/tbbr_cot.c:544:23: error: ISO C does not allow
   extra ';' outside of a function [-Werror=pedantic]

   This has been fixed both in the mbed TLS authentication module
   as well as in the certificate generation tool. Note that the latter
   code didn't need fixing since it is not built with '-pedantic' but
   the change has been propagated for consistency.

   Also fixed the REGISTER_KEYS() and REGISTER_EXTENSIONS() macros,
   which were suffering from the same issue.

 * Fixes a pointer type.

   It was causing the following error message:

   drivers/auth/mbedtls/mbedtls_crypto.c: In function 'verify_hash':
   drivers/auth/mbedtls/mbedtls_crypto.c:177:42: error: pointer of
   type 'void *' used in arithmetic [-Werror=pointer-arith]

Change-Id: I7b7a04ef711efd65e17b5be26990d1a0d940257d