pinctrl: single: Add allocation failure checking of saved_vals

Currently saved_vals is being allocated and there is no check for
failed allocation (which is more likely than normal when using
GFP_ATOMIC).  Fix this by checking for a failed allocation and
propagating this error return down the the caller chain.

Detected by CoverityScan, CID#1469841 ("Dereference null return value")
Fixes: 88a1dbdec6 ("pinctrl: pinctrl-single: Add functions to save and restore pinctrl context")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Johan Hovold <johan@kernel.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-single.c

@@ -1590,8 +1590,11 @@ static int pcs_save_context(struct pcs_device *pcs)
 
 	mux_bytes = pcs->width / BITS_PER_BYTE;
 
-	if (!pcs->saved_vals)
+	if (!pcs->saved_vals) {
 		pcs->saved_vals = devm_kzalloc(pcs->dev, pcs->size, GFP_ATOMIC);
+		if (!pcs->saved_vals)
+			return -ENOMEM;
+	}
 
 	switch (pcs->width) {
 	case 64:
@@ -1651,8 +1654,13 @@ static int pinctrl_single_suspend(struct platform_device *pdev,
 	if (!pcs)
 		return -EINVAL;
 
-	if (pcs->flags & PCS_CONTEXT_LOSS_OFF)
-		pcs_save_context(pcs);
+	if (pcs->flags & PCS_CONTEXT_LOSS_OFF) {
+		int ret;
+
+		ret = pcs_save_context(pcs);
+		if (ret < 0)
+			return ret;
+	}
 
 	return pinctrl_force_sleep(pcs->pctl);
 }