V4L/DVB (6621): tda827x: fix NULL pointer dereference during tda827x_probe_version

Fix the following oops:

[  750.807586] CPU:    1
[  750.807587] EIP:    0060:[<f9dde2a3>]    Tainted: P       VLI
[  750.807589] EFLAGS: 00010296   (2.6.22-14-generic #1)
[  750.807599] EIP is at tda827x_probe_version+0xc3/0x130 [tda827x]
[  750.807603] eax: 00000000   ebx: f5a45a00   ecx: 00000000   edx: 00000001
[  750.807607] esi: f9de05ac   edi: e9b897e0   ebp: ed8015ac   esp: ed735f58
[  750.807611] ds: 007b   es: 007b   fs: 00d8  gs: 0000  ss: 0068
[  750.807615] Process kdvb-fe-1 (pid: 10662, ti=ed734000 task=d3b76530 task.ti=ed734000)
[  750.807618] Stack: f9e23972 00000038 ed735fd0 00010060 41ae0001 ed735f73 88b89608 e9b89608
[  750.807629]        e9b89608 ed801400 f9dde338 e9b89608 f9b2a46b 000000ae 00000a18 d3b76640
[  750.807639]        fffffffc f9b2bad6 00000003 f4433e68 e962b8c0 f4433e64 00000292 ed735fd0
[  750.807649] Call Trace:
[  750.807653]  [<f9e23972>] tda10046_init+0x2d2/0x6c0 [tda1004x]
[  750.807700]  [<f9dde338>] tda827x_initial_init+0x8/0x20 [tda827x]
[  750.807713]  [<f9b2a46b>] dvb_frontend_init+0x2b/0x60 [dvb_core]
[  750.807745]  [<f9b2bad6>] dvb_frontend_thread+0x66/0x2f0 [dvb_core]
[  750.807780]  [complete+64/96] complete+0x40/0x60
[  750.807805]  [<f9b2ba70>] dvb_frontend_thread+0x0/0x2f0 [dvb_core]
[  750.807822]  [kthread+66/112] kthread+0x42/0x70
[  750.807828]  [kthread+0/112] kthread+0x0/0x70
[  750.807841]  [kernel_thread_helper+7/16] kernel_thread_helper+0x7/0x10
[  750.807869]  =======================
[  750.807872] Code: 8b 74 24 20 8b 7c 24 24 83 c4 28 c3 8b 0d 00 0c de f9 85 c9 75 42 be e0 04 de f9 81 c7 0c 01 00 00 b9 33 00 00 00 f3 a5 8b 43 08 <c7> 40 14 50 e3 dd f9 8b 5c 24 1c 31 c0 8b 74 24 20 8b 7c 24 24
[  750.807925] EIP: [<f9dde2a3>] tda827x_probe_version+0xc3/0x130 [tda827x] SS:ESP 0068:ed735f58
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/dvb/frontends/tda827x.c

@@ -796,11 +796,13 @@ static int tda827x_probe_version(struct dvb_frontend *fe)
 		dprintk("tda827x tuner found\n");
 		fe->ops.tuner_ops.init  = tda827x_init;
 		fe->ops.tuner_ops.sleep = tda827xo_sleep;
-		priv->cfg->agcf = tda827xo_agcf;
+		if (priv->cfg)
+			priv->cfg->agcf = tda827xo_agcf;
 	} else {
 		dprintk("tda827xa tuner found\n");
 		memcpy(&fe->ops.tuner_ops, &tda827xa_tuner_ops, sizeof(struct dvb_tuner_ops));
-		priv->cfg->agcf = tda827xa_agcf;
+		if (priv->cfg)
+			priv->cfg->agcf = tda827xa_agcf;
 	}
 	return 0;
 }