media: rc: cec devices do not have a lirc chardev

This fixes an oops in ir_lirc_scancode_event().

BUG: unable to handle kernel NULL pointer dereference at 0000000000000038
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 9 PID: 27687 Comm: kworker/9:2 Tainted: P           OE 4.18.12-200.fc28.x86_64 #1
Hardware name: Supermicro C7X99-OCE-F/C7X99-OCE-F, BIOS 2.1a 06/15/2018
Workqueue: events pulse8_irq_work_handler [pulse8_cec]
RIP: 0010:ir_lirc_scancode_event+0x3d/0xb0 [rc_core]
Code: 8d ae b4 07 00 00 49 81 c6 b8 07 00 00 53 e8 4a df c3 d5 48 89 ef 49 89 45 00 e8 4e 84 41 d6 49 8b 1e 49 89 c4 4c 39 f3 74 58 <8b> 43 38 8b 53 40 89 c1 2b 4b 3c 39 ca 72 41 21 d0 49 8b 7d 00 49
RSP: 0018:ffffaa10e3c07d58 EFLAGS: 00010017
RAX: 0000000000000002 RBX: 0000000000000000 RCX: 0000000000000018
RDX: 0000000000000001 RSI: 00316245397fa93c RDI: ffff966d31c8d7b4
RBP: ffff966d31c8d7b4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000003 R11: ffffaa10e3c07e28 R12: 0000000000000002
R13: ffffaa10e3c07d88 R14: ffff966d31c8d7b8 R15: 0000000000000073
FS:  0000000000000000(0000) GS:ffff966d3f440000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000038 CR3: 00000009d820a003 CR4: 00000000003606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 ir_do_keydown+0x75/0x260 [rc_core]
 rc_keydown+0x54/0xc0 [rc_core]
 cec_received_msg_ts+0xaa8/0xaf0 [cec]
 process_one_work+0x1a1/0x350
 worker_thread+0x30/0x380
 ? pwq_unbound_release_workfn+0xd0/0xd0
 kthread+0x112/0x130
 ? kthread_create_worker_on_cpu+0x70/0x70
 ret_from_fork+0x35/0x40
Modules linked in: rc_tt_1500 dvb_usb_dvbsky dvb_usb_v2 uas usb_storage fuse vhost_net vhost tap xt_CHECKSUM iptable_mangle ip6t_REJECT nf_reject_ipv6 tun 8021q garp mrp xt_nat macvlan xfs devlink ebta
 si2157 si2168 cx25840 cx23885 kvm altera_ci tda18271 joydev ir_rc6_decoder rc_rc6_mce crct10dif_pclmul crc32_pclmul ghash_clmulni_intel intel_cstate intel_uncore altera_stapl m88ds3103 tveeprom cx2341
 mxm_wmi igb crc32c_intel megaraid_sas dca i2c_algo_bit wmi vfio_pci irqbypass vfio_virqfd vfio_iommu_type1 vfio i2c_dev
CR2: 0000000000000038

Cc: <stable@vger.kernel.org> # v4.16+
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/rc/rc-main.c

@@ -695,6 +695,7 @@ void rc_repeat(struct rc_dev *dev)
 			 (dev->last_toggle ? LIRC_SCANCODE_FLAG_TOGGLE : 0)
 	};
 
+	if (dev->allowed_protocols != RC_PROTO_BIT_CEC)
 		ir_lirc_scancode_event(dev, &sc);
 
 	spin_lock_irqsave(&dev->keylock, flags);
@@ -735,6 +736,7 @@ static void ir_do_keydown(struct rc_dev *dev, enum rc_proto protocol,
 		.keycode = keycode
 	};
 
+	if (dev->allowed_protocols != RC_PROTO_BIT_CEC)
 		ir_lirc_scancode_event(dev, &sc);
 
 	if (new_event && dev->keypressed)