brcmfmac: of: Use devm_kstrdup for board_type & check for errors

This was missing a NULL check, and we can collapse the strlen/alloc/copy
into a devm_kstrdup().

Signed-off-by: Hector Martin <marcan@marcan.st>

drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c

@@ -79,8 +79,12 @@ void brcmf_of_probe(struct device *dev, enum brcmf_bus_type bus_type,
 
 		/* get rid of '/' in the compatible string to be able to find the FW */
 		len = strlen(tmp) + 1;
-		board_type = devm_kzalloc(dev, len, GFP_KERNEL);
-		strscpy(board_type, tmp, len);
+		board_type = devm_kstrdup(dev, tmp, GFP_KERNEL);
+		if (!board_type) {
+			brcmf_err("out of memory allocating board_type\n");
+			of_node_put(root);
+			return;
+		}
 		for (i = 0; i < board_type[i]; i++) {
 			if (board_type[i] == '/')
 				board_type[i] = '-';