staging: iio: tsl2583: remove unnecessary memset call

The entries in the lux table (als_device_lux) can be updated via sysfs
through the function in_illuminance_lux_table_store(). The last row in
the table must be terminated with values that are zero. The sysfs code
already ensures that the last row is all zeros. The call to memset to
clear out the table is not needed so this patch removes the unnecessary
call.

Signed-off-by: Brian Masney <masneyb@onstation.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>