spi: use sysfs_emit() for printing statistics and add trailing newline

Use dedicated function sysfs_emit() that does some extra checking,
e.g. to ensure that no more than PAGESIZE bytes are written.
In addition add a trailing newline to the output, that makes it
better readable from the console.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/56e1588d-d53b-73e9-fdc8-7fe30bf91f11@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi.c

@@ -143,7 +143,7 @@ static ssize_t spi_statistics_##name##_show(struct spi_statistics *stat, \
 	unsigned long flags;						\
 	ssize_t len;							\
 	spin_lock_irqsave(&stat->lock, flags);				\
-	len = sprintf(buf, format_string, stat->field);			\
+	len = sysfs_emit(buf, format_string "\n", stat->field);		\
 	spin_unlock_irqrestore(&stat->lock, flags);			\
 	return len;							\
 }									\