media: ti-vpe: cal: Rename cal_csi2_phy base_fields to fields

The cal_csi2_phy structure has lost its 'fields' field that used to
clash with the 'base_fields' field. Rename base_fields to fields.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>