target: clarify usage of coreid

By definition in `target/target.h`, `coreid` is not a unique identifier
of a target -- it can be the same for targets on different TAPs.

Change-Id: Ifce78da55fffe28dd8b6b06ecae7d8c4e305c0a2
Signed-off-by: Evgeniy Naydanov <evgeniy.naydanov@syntacore.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/7997
Tested-by: jenkins
Reviewed-by: Marek Vrbka <marek.vrbka@codasip.com>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

src/target/smp.c

@@ -132,6 +132,9 @@ COMMAND_HANDLER(handle_smp_gdb_command)
 {
 	struct target *target = get_current_target(CMD_CTX);
 	int retval = ERROR_OK;
+
+	LOG_WARNING(DEPRECATED_MSG);
+
 	if (!list_empty(target->smp_targets)) {
 		if (CMD_ARGC == 1) {
 			int coreid = 0;