clk-gate: fix bit # check in clk_register_gate()

commit 2e9dcdae upstream.

In case CLK_GATE_HIWORD_MASK flag is passed to clk_register_gate(), the bit #
should be no higher than 15, however the corresponding check is obviously off-
by-one.

Fixes: 04577994 ("clk: gate: add CLK_GATE_HIWORD_MASK")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Michael Turquette <mturquette@linaro.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/clk/clk-gate.c

@@ -128,7 +128,7 @@ struct clk *clk_register_gate(struct device *dev, const char *name,
 	struct clk_init_data init;
 
 	if (clk_gate_flags & CLK_GATE_HIWORD_MASK) {
-		if (bit_idx > 16) {
+		if (bit_idx > 15) {
 			pr_err("gate bit exceeds LOWORD field\n");
 			return ERR_PTR(-EINVAL);
 		}