ltc: ctr: fix counter increment when LTC_FAST is defined

In CTR mode the counter needs to be incremented upon completion of each
block. Unfortunately, if there is no crypto acceleration
(accel_ctr_encrypt == NULL) and if LTC_FAST is defined, this does not
happen. Add the missing call to fix the issue.

Reported-by: Jork Loeser <jork.loeser@microsoft.com>
Closes: https://lists.trustedfirmware.org/archives/list/op-tee@lists.trustedfirmware.org/thread/J4MMZPCM2MNKC2KWAXZUMTVEJP56U6OI/
Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>

core/lib/libtomcrypt/src/modes/ctr/ctr_encrypt.c

@@ -61,6 +61,7 @@ static int s_ctr_encrypt(const unsigned char *pt, unsigned char *ct, unsigned lo
        ct         += ctr->blocklen;
        len        -= ctr->blocklen;
        ctr->padlen = ctr->blocklen;
+       s_ctr_increment_counter(ctr);
        continue;
       }
 #endif