bus: imx-weim: Remove VLA usage

In the quest to remove all stack VLA usage from the kernel[1], this
switches to using a maximum size and adds a sanity check.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=[e-mail]

Cc: Shawn Guo <[e-mail]>
Cc: Sascha Hauer <[e-mail]>
Cc: Pengutronix Kernel Team <[e-mail]>
Cc: Fabio Estevam <[e-mail]>
Cc: NXP Linux Team <[e-mail]>
Signed-off-by: Kees Cook <[e-mail]>
Reviewed-by: Arnd Bergmann <[e-mail]>
Acked-by: Shawn Guo <[e-mail]>

drivers/bus/imx-weim.c

···
 	.cs_stride	= 0x18,
 };
 
+#define MAX_CS_REGS_COUNT	6
+
 static const struct of_device_id weim_id_table[] = {
 	/* i.MX1/21 */
 	{ .compatible = "fsl,imx1-weim", .data = &imx1_weim_devtype, },
···
 static int __init weim_timing_setup(struct device_node *np, void __iomem *base,
 				    const struct imx_weim_devtype *devtype)
 {
-	u32 cs_idx, value[devtype->cs_regs_count];
+	u32 cs_idx, value[MAX_CS_REGS_COUNT];
 	int i, ret;
+
+	if (WARN_ON(devtype->cs_regs_count > MAX_CS_REGS_COUNT))
+		return -EINVAL;
 
 	/* get the CS index from this child node's "reg" property. */
 	ret = of_property_read_u32(np, "reg", &cs_idx);