util/spkmodem_recv: Move global variable: pulse

It is only used by a single function.

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/spkmodem_recv/spkmodem-recv.c

@@ -22,7 +22,6 @@
 #define FLUSH_TIMEOUT 1
 
 signed short frame[2 * SAMPLES_PER_FRAME];
-signed short pulse[2 * SAMPLES_PER_FRAME];
 int f1, f2;
 int lp = 0;
 int ascii_bit = 7;
@@ -76,6 +75,7 @@ void
 fetch_sample(void)
 {
 	static int ringpos = 0;
+	static signed short pulse[2 * SAMPLES_PER_FRAME];
 
 	f1 -= pulse[ringpos];
 	f1 += pulse[(ringpos + SAMPLES_PER_FRAME) % (2 * SAMPLES_PER_FRAME)];