treewide: Remove uninitialized_var() usage

Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings
(e.g. "unused variable"). If the compiler thinks it is uninitialized,
either simply initialize the variable or make compiler changes.

In preparation for removing[2] the[3] macro[4], remove all remaining
needless uses with the following script:

git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \
	xargs perl -pi -e \
		's/\buninitialized_var\(([^\)]+)\)/\1/g;
		 s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;'

drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid
pathological white-space.

No outstanding warnings were found building allmodconfig with GCC 9.3.0
for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64,
alpha, and m68k.

[1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/

Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5
Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB
Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers
Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs
Signed-off-by: Kees Cook <keescook@chromium.org>

drivers/infiniband/hw/mlx5/cq.c

@@ -925,8 +925,8 @@ int mlx5_ib_create_cq(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
 	struct mlx5_ib_dev *dev = to_mdev(ibdev);
 	struct mlx5_ib_cq *cq = to_mcq(ibcq);
 	u32 out[MLX5_ST_SZ_DW(create_cq_out)];
-	int uninitialized_var(index);
-	int uninitialized_var(inlen);
+	int index;
+	int inlen;
 	u32 *cqb = NULL;
 	void *cqc;
 	int cqe_size;
@@ -1246,7 +1246,7 @@ int mlx5_ib_resize_cq(struct ib_cq *ibcq, int entries, struct ib_udata *udata)
 	__be64 *pas;
 	int page_shift;
 	int inlen;
-	int uninitialized_var(cqe_size);
+	int cqe_size;
 	unsigned long flags;
 
 	if (!MLX5_CAP_GEN(dev->mdev, cq_resize)) {

drivers/infiniband/hw/mlx5/devx.c

@@ -2536,7 +2536,7 @@ static ssize_t devx_async_event_read(struct file *filp, char __user *buf,
 {
 	struct devx_async_event_file *ev_file = filp->private_data;
 	struct devx_event_subscription *event_sub;
-	struct devx_async_event_data *uninitialized_var(event);
+	struct devx_async_event_data *event;
 	int ret = 0;
 	size_t eventsz;
 	bool omit_data;

drivers/infiniband/hw/mlx5/wr.c

@@ -1249,7 +1249,7 @@ int mlx5_ib_post_send(struct ib_qp *ibqp, const struct ib_send_wr *wr,
 	struct mlx5_wqe_xrc_seg *xrc;
 	struct mlx5_bf *bf;
 	void *cur_edge;
-	int uninitialized_var(size);
+	int size;
 	unsigned long flags;
 	unsigned int idx;
 	int err = 0;