Format UUID strings correctly

Prior to this patch although GlobalPlatform specifies that TAs and such
are identified with UUIDs, we don't format them quite right when turning
them into strings. Per https://www.ietf.org/rfc/rfc4122.txt, there
should be another hyphen after the first two bytes of clockSeqAndNode.

Unfortunately, fixing this breaks compatibility between how TAs are
built, and when the OS loads them.

With this patch UUID string are formated with the additional hyphen as
for instance: f81d4fae-7dec-11d0-a765-00a0c91e6bf6

Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>
Fixes: OP-TEE/optee_os#857
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

tee-supplicant/src/teec_ta_load.c

@@ -95,7 +95,7 @@ static int try_load_secure_module(const char* prefix,
 	}
 
 	n = snprintf(fname, PATH_MAX,
-		     "%s/%s/%08x-%04x-%04x-%02x%02x%02x%02x%02x%02x%02x%02x.ta",
+		     "%s/%s/%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x.ta",
 		     prefix, dev_path,
 		     destination->timeLow,
 		     destination->timeMid,