nl80211: fix VENDOR_CMD_RAW_DATA

Since ERR_PTR() is an inline, not a macro, just open-code it
here so it's usable as an initializer, fixing the build in
brcmfmac.
Reported-by: Arend Van Spriel <arend.vanspriel@broadcom.com>
Fixes: 901bb989 ("nl80211: require and validate vendor command policy")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -4170,7 +4170,7 @@ struct sta_opmode_info {
 	u8 rx_nss;
 };
 
-#define VENDOR_CMD_RAW_DATA ((const struct nla_policy *)ERR_PTR(-ENODATA))
+#define VENDOR_CMD_RAW_DATA ((const struct nla_policy *)(long)(-ENODATA))
 
 /**
  * struct wiphy_vendor_command - vendor command definition