media: dvb-usb: avoid -Wempty-body warnings

Building with 'make W=1' shows many warnings -Wempty-body warnings like

drivers/media/usb/dvb-usb/vp702x-fe.c: In function 'vp702x_fe_set_frontend':
drivers/media/usb/dvb-usb/vp702x-fe.c:190:46: error: suggest braces around empty body in an 'else' statement [-Werror=empty-body]
  190 |                 deb_fe("tuning succeeded.\n");
drivers/media/usb/dvb-usb/dtt200u.c: In function 'dtt200u_rc_query':
drivers/media/usb/dvb-usb/dtt200u.c:124:58: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
  124 |                 deb_info("st->data: %*ph\n", 5, st->data);
drivers/media/usb/dvb-usb/m920x.c: In function 'm920x_rc_query':
drivers/media/usb/dvb-usb/m920x.c:207:58: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
  207 |                 deb("Unknown rc key %02x\n", rc_state[1]);

Change the empty dprintk() macros to no_printk(), which avoids this
warning and adds format string checking.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/usb/dvb-usb/dvb-usb.h

@@ -28,18 +28,19 @@
 
 /* debug */
 #ifdef CONFIG_DVB_USB_DEBUG
-#define dprintk(var,level,args...) \
-	    do { if ((var & level)) { printk(args); } } while (0)
+#define dprintk(var, level, args...) \
+	    do { if (((var) & (level))) { printk(args); } } while (0)
 
-#define debug_dump(b,l,func) {\
+#define debug_dump(b, l, func) {\
 	int loop_; \
-	for (loop_ = 0; loop_ < l; loop_++) func("%02x ", b[loop_]); \
+	for (loop_ = 0; loop_ < (l); loop_++) \
+		func("%02x ", b[loop_]); \
 	func("\n");\
 }
 #define DVB_USB_DEBUG_STATUS
 #else
-#define dprintk(args...)
-#define debug_dump(b,l,func)
+#define dprintk(var, level, args...) no_printk(args)
+#define debug_dump(b, l, func) do { } while (0)
 
 #define DVB_USB_DEBUG_STATUS " (debugging is not enabled)"