ALSA: hda/ca0132 - Replace zero-length array with flexible-array member

The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertenly introduced[3] to the codebase from now on.

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] KSPP#21
[3] commit 7649773 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <[email protected]>
Link: https://lore.kernel.org/r/20200211194403.GA10318@embeddedor
Signed-off-by: Takashi Iwai <[email protected]>

sound/pci/hda/patch_ca0132.c

@@ -2698,7 +2698,7 @@ struct dsp_image_seg {
 	u32 magic;
 	u32 chip_addr;
 	u32 count;
-	u32 data[0];
+	u32 data[];
 };
 
 static const u32 g_magic_value = 0x4c46584d;