spi: tools: Make default_tx/rx and input_tx static

Fix the following sparse warning:

./spidev_test.c:50:9: warning: symbol 'default_tx' was not declared. Should it be static?
./spidev_test.c:59:9: warning: symbol 'default_rx' was not declared. Should it be static?
./spidev_test.c:60:6: warning: symbol 'input_tx' was not declared. Should it be static?
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Link: https://lore.kernel.org/r/1591880212-13479-1-git-send-email-zhangqing@loongson.cnSigned-off-by: Mark Brown <broonie@kernel.org>

tools/spi/spidev_test.c

@@ -47,7 +47,7 @@ static int transfer_size;
 static int iterations;
 static int interval = 5; /* interval in seconds for showing transfer rate */
 
-uint8_t default_tx[] = {
+static uint8_t default_tx[] = {
 	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
 	0x40, 0x00, 0x00, 0x00, 0x00, 0x95,
 	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
@@ -56,8 +56,8 @@ uint8_t default_tx[] = {
 	0xF0, 0x0D,
 };
 
-uint8_t default_rx[ARRAY_SIZE(default_tx)] = {0, };
-char *input_tx;
+static uint8_t default_rx[ARRAY_SIZE(default_tx)] = {0, };
+static char *input_tx;
 
 static void hex_dump(const void *src, size_t length, size_t line_size,
 		     char *prefix)