greybus: remove stray nul byte in apb_log_enable_read output

Including a nul byte in the otherwise human-readable ascii output
from this debugfs file is probably not intended.

Acked-by: Alex Elder <elder@linaro.org>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Link: https://lore.kernel.org/r/20210326152254.733066-1-linux@rasmusvillemoes.dk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/greybus/es2.c

@@ -1171,7 +1171,7 @@ static ssize_t apb_log_enable_read(struct file *f, char __user *buf,
 	char tmp_buf[3];
 
 	sprintf(tmp_buf, "%d\n", enable);
-	return simple_read_from_buffer(buf, count, ppos, tmp_buf, 3);
+	return simple_read_from_buffer(buf, count, ppos, tmp_buf, 2);
 }
 
 static ssize_t apb_log_enable_write(struct file *f, const char __user *buf,