According to the R-Car Series, 3rd Generation Hardware User’s Manual
Rev. 2.30, the parent clock of the Video Input Module (VIN) on R-Car D3
is S3D1.  Update the driver to match the documentation.

This has no functional impact, as both S1D2 and S3D1 have the same clock
rate, and are always-on clocks.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/9b655843a260e06fa6f3349cdafac180e2bf38a5.1676368776.git.geert+renesas@glider.be