[media] dib9000: fix explicit lock mismatches

There are several error paths, where &state->platform.risc.mem_mbx_lock
is not unlocked. The patch fixes it.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/dvb/frontends/dib9000.c b/drivers/media/dvb/frontends/dib9000.c
index 863ef3c..d96b6a1 100644
--- a/drivers/media/dvb/frontends/dib9000.c
+++ b/drivers/media/dvb/frontends/dib9000.c
@@ -2208,6 +2208,7 @@
 
 	DibAcquireLock(&state->platform.risc.mem_mbx_lock);
 	if (dib9000_fw_memmbx_sync(state, FE_SYNC_CHANNEL) < 0) {
+		DibReleaseLock(&state->platform.risc.mem_mbx_lock);
 		ret = -EIO;
 		goto error;
 	}
@@ -2233,8 +2234,10 @@
 	u16 val;
 
 	DibAcquireLock(&state->platform.risc.mem_mbx_lock);
-	if (dib9000_fw_memmbx_sync(state, FE_SYNC_CHANNEL) < 0)
+	if (dib9000_fw_memmbx_sync(state, FE_SYNC_CHANNEL) < 0) {
+		DibReleaseLock(&state->platform.risc.mem_mbx_lock);
 		return -EIO;
+	}
 	dib9000_risc_mem_read(state, FE_MM_R_FE_MONITOR, (u8 *) c, 16 * 2);
 	DibReleaseLock(&state->platform.risc.mem_mbx_lock);
 
@@ -2291,6 +2294,7 @@
 	DibAcquireLock(&state->demod_lock);
 	DibAcquireLock(&state->platform.risc.mem_mbx_lock);
 	if (dib9000_fw_memmbx_sync(state, FE_SYNC_CHANNEL) < 0) {
+		DibReleaseLock(&state->platform.risc.mem_mbx_lock);
 		ret = -EIO;
 		goto error;
 	}