[media] tda18212: tda18218: use 'val' if initialized

Commits e666a44f ("[media] tda18212:
silence compiler warning") and e0e52d4e
("[media] tda18218: silence compiler warning") silenced warnings
equivalent to these:
    drivers/media/tuners/tda18212.c: In function ‘tda18212_attach’:
    drivers/media/tuners/tda18212.c:299:2: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized]
    drivers/media/tuners/tda18218.c: In function ‘tda18218_attach’:
    drivers/media/tuners/tda18218.c:305:2: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized]
But in both cases 'val' will still be used uninitialized if the calls
of tda18212_rd_reg() or tda18218_rd_reg() fail. Fix this by only
printing the "chip id" if the calls of those functions were successful.
This allows to drop the uninitialized_var() stopgap measure.
Also stop printing the return values of tda18212_rd_reg() or
tda18218_rd_reg(), as these are not interesting.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Acked-by: Antti Palosaari <crope@iki.fi>
Reviewed-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>