gdbstub: Clear unused variables in gdb_handle_packet

Signed-off-by: Jon Doron <arilou@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20190529064148.19856-20-arilou@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

gdbstub.c

@@ -2288,17 +2288,11 @@ static void handle_target_halt(GdbCmdContext *gdb_ctx, void *user_ctx)
 
 static int gdb_handle_packet(GDBState *s, const char *line_buf)
 {
-    const char *p;
-    int ch;
-    uint8_t mem_buf[MAX_PACKET_LENGTH];
-    char buf[sizeof(mem_buf) + 1 /* trailing NUL */];
     const GdbCmdParseEntry *cmd_parser = NULL;
 
     trace_gdbstub_io_command(line_buf);
 
-    p = line_buf;
-    ch = *p++;
-    switch(ch) {
+    switch (line_buf[0]) {
     case '!':
         put_packet(s, "OK");
         break;
@@ -2515,8 +2509,7 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
         break;
     default:
         /* put empty packet */
-        buf[0] = '\0';
-        put_packet(s, buf);
+        put_packet(s, "");
         break;
     }