clk: visconti: prevent array overflow in visconti_clk_register_gates()

This code was using -1 to represent that there was no reset function.
Unfortunately, the -1 was stored in u8 so the if (clks[i].rs_id >= 0)
condition was always true.  This lead to an out of bounds access in
visconti_clk_register_gates().

Fixes: b4cbe606

 ("clk: visconti: Add support common clock driver and reset driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20220316083533.GA30941@kili


Acked-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>