media: atomisp: Don't use ifdef on IS_ISP2401

IS_ISP2401 is a function like macro which is always defined, so it must
not be used together with #ifdef. #ifdef checks should check for
"ISP2401", not "IS_ISP2401".

Link: https://lore.kernel.org/linux-media/20220116215204.307649-2-hdegoede@redhat.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>