clk: mediatek: clk-mt6797: Add check for mtk_alloc_clk_data

Add the check for the return value of mtk_alloc_clk_data() in order to
avoid NULL pointer dereference.

Fixes: 96596aa06628 ("clk: mediatek: add clk support for MT6797")
Signed-off-by: Jiasheng Jiang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: AngeloGioacchino Del Regno <[e-mail]>
Signed-off-by: Stephen Boyd <[e-mail]>

drivers/clk/mediatek/clk-mt6797.c

···
 		return PTR_ERR(base);
 
 	clk_data = mtk_alloc_clk_data(CLK_TOP_NR);
+	if (!clk_data)
+		return -ENOMEM;
 
 	mtk_clk_register_factors(top_fixed_divs, ARRAY_SIZE(top_fixed_divs),
 				 clk_data);
···
 
 	if (!infra_clk_data) {
 		infra_clk_data = mtk_alloc_clk_data(CLK_INFRA_NR);
+		if (!infra_clk_data)
+			return;
 
 		for (i = 0; i < CLK_INFRA_NR; i++)
 			infra_clk_data->hws[i] = ERR_PTR(-EPROBE_DEFER);
···
 
 	if (!infra_clk_data) {
 		infra_clk_data = mtk_alloc_clk_data(CLK_INFRA_NR);
+		if (!infra_clk_data)
+			return -ENOMEM;
 	} else {
 		for (i = 0; i < CLK_INFRA_NR; i++) {
 			if (infra_clk_data->hws[i] == ERR_PTR(-EPROBE_DEFER))