RDMA/erdma: Replace zero-length arrays with flexible-array members

Zero-length arrays are deprecated[1] and we are moving towards
adopting C99 flexible-array members instead. So, replace zero-length
arrays, in a couple of structures, with flex-array members.

This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
routines on memcpy() and help us make progress towards globally
enabling -fstrict-flex-arrays=3 [2].

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays [1]
Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [2]
Link: KSPP#78
Signed-off-by: Gustavo A. R. Silva <[email protected]>
Link: https://lore.kernel.org/r/Y7zCBqwC1LtabRJ9@work
Reviewed-by: Kees Cook <[email protected]>
Acked-by: Cheng Xu <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>

drivers/infiniband/hw/erdma/erdma_hw.h

@@ -397,7 +397,7 @@ struct erdma_write_sqe {
 
 	__le32 rsvd;
 
-	struct erdma_sge sgl[0];
+	struct erdma_sge sgl[];
 };
 
 struct erdma_send_sqe {
@@ -408,7 +408,7 @@ struct erdma_send_sqe {
 	};
 
 	__le32 length;
-	struct erdma_sge sgl[0];
+	struct erdma_sge sgl[];
 };
 
 struct erdma_readreq_sqe {