media: qcom: camss: Rename camss-csid-780.c to camss-csid-gen3.c

media: qcom: camss: Rename camss-csid-780.c to camss-csid-gen3.c

Rename the file camss-csid-780.c to camss-csid-gen3.c to enable
reuse of CSID logic across multiple SoCs.

The lemans(sa8775p) SoC includes CSID 690, which is functionally very
similar to CSID 780, with only minor differences in register
bitfields. This rename prepares the codebase for supporting
additional SoCs without duplicating CSID logic.

Signed-off-by: Vikram Sharma <quic_vikramsa@quicinc.com>
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Bryan O'Donoghue <bod@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>