ALSA: firewire-lib: Fix uninitialized variable err issue

The check of error is just done for the case that CIP header is available.

This commit moves auto variable into the branch to process CIP header.

Addresses-Coverity: ("Uninitialized scalar variable")
Fixes: c09010ee ("ALSA: firewire-lib: handle the case that empty isochronous packet payload for CIP")
Suggested-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20210520130409.GA170303@workstationSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/amdtp-stream.c

@@ -652,7 +652,6 @@ static int parse_ir_ctx_header(struct amdtp_stream *s, unsigned int cycle,
 	unsigned int payload_length;
 	const __be32 *cip_header;
 	unsigned int cip_header_size;
-	int err;
 
 	payload_length = be32_to_cpu(ctx_header[0]) >> ISO_DATA_LENGTH_SHIFT;
 
@@ -670,6 +669,8 @@ static int parse_ir_ctx_header(struct amdtp_stream *s, unsigned int cycle,
 
 	if (cip_header_size > 0) {
 		if (payload_length >= cip_header_size) {
+			int err;
+
 			cip_header = ctx_header + IR_CTX_HEADER_DEFAULT_QUADLETS;
 			err = check_cip_header(s, cip_header, payload_length - cip_header_size,
 					       data_blocks, data_block_counter, syt);
@@ -683,7 +684,6 @@ static int parse_ir_ctx_header(struct amdtp_stream *s, unsigned int cycle,
 		}
 	} else {
 		cip_header = NULL;
-		err = 0;
 		*data_blocks = payload_length / sizeof(__be32) / s->data_block_quadlets;
 		*syt = 0;
 
@@ -694,7 +694,7 @@ static int parse_ir_ctx_header(struct amdtp_stream *s, unsigned int cycle,
 	trace_amdtp_packet(s, cycle, cip_header, payload_length, *data_blocks,
 			   *data_block_counter, packet_index, index);
 
-	return err;
+	return 0;
 }
 
 // In CYCLE_TIMER register of IEEE 1394, 7 bits are used to represent second. On