clk: rs9: Limit check to vendor ID in VID register

Extract only vendor ID from VID register, the top 4 bits are
revision ID which are not useful for the vendor ID check.

Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Link: https://lore.kernel.org/r/20231113221949.111964-2-marek.vasut+renesas@mailbox.org


Signed-off-by: Stephen Boyd <sboyd@kernel.org>