phy: renesas: rcar-gen3-usb2: Set timing registers only once

phy: renesas: rcar-gen3-usb2: Set timing registers only once

phy-rcar-gen3-usb2 driver exports 4 PHYs. The timing registers are common
to all PHYs. There is no need to set them every time a PHY is initialized.
Set timing register only when the 1st PHY is initialized.

Fixes: f3b5a8d9b50d ("phy: rcar-gen3-usb2: Add R-Car Gen3 USB2 PHY driver")
Cc: stable@vger.kernel.org
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Link: https://lore.kernel.org/r/20250507125032.565017-6-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>