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>