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.com


Signed-off-by: Mark Brown <broonie@kernel.org>