[media] r820t: fix imr calibration

The r820t_imr() calibration function of the Rafael Micro R820T tuner
generates this error at every tune attempt:
r820t 0-001a: No valid PLL values for 2252021 kHz!
The function was inspired by the original Realtek driver for rtl2832 devices
with the r820t tuner; anyway, in the original code the XTAL frequency of
the tuner was expressed in KHz, while in the kernel driver it is expressed
in Hz; so the calibration failed because of an out-of-range initial value.
The final result of the computation is then passed to the r820t_set_mux()
and r820t_set_pll() functions, but the conversion from KHz to Hz is already
correctly implemented.

Signed-off-by: Gianluca Gennari <gennarone@gmail.com>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/tuners/r820t.c

@@ -1857,9 +1857,9 @@ static int r820t_imr(struct r820t_priv *priv, unsigned imr_mem, bool im_flag)
 	int reg18, reg19, reg1f;
 
 	if (priv->cfg->xtal > 24000000)
-		ring_ref = priv->cfg->xtal / 2;
+		ring_ref = priv->cfg->xtal / 2000;
 	else
-		ring_ref = priv->cfg->xtal;
+		ring_ref = priv->cfg->xtal / 1000;
 
 	n_ring = 15;
 	for (n = 0; n < 16; n++) {