media: staging/intel-ipu3: css: Correctly reset some memory

The intent here is to reset the whole 'scaler_coeffs_luma' array, not just
the first element.

Fixes: e11110a5 ("media: staging/intel-ipu3: css: Compute and program ccs")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Bingbu Cao <bingbu.cao@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>