dmaengine: sa11x0: 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 inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by this change:

"Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

---
 drivers/dma/sa11x0-dma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index afb68055ed1b..0fa7f14a65a1 100644
@@ -78,7 +78,7 @@ struct sa11x0_dma_desc {
 	bool			cyclic;
 
 	unsigned		sglen;
-	struct sa11x0_dma_sg	sg[0];
+	struct sa11x0_dma_sg	sg[];
 };
 
 struct sa11x0_dma_phy;

2.25.0

Applied, thanks

~Vinod