RADIUS client: Fix void-pointer-to-enum-cast warning

Found using x86_64-cros-linux-gnu-clang (Chromium OS
12.0_pre416183_p20210305-r3 clang version 12.0.0):

radius_client.c:818:24: warning: cast to smaller integer ...
        RadiusType msg_type = (RadiusType) sock_ctx;

Signed-off-by: Joshua Emele <jemele@chromium.org>

src/radius/radius_client.c

@@ -815,7 +815,7 @@ static void radius_client_receive(int sock, void *eloop_ctx, void *sock_ctx)
 {
 	struct radius_client_data *radius = eloop_ctx;
 	struct hostapd_radius_servers *conf = radius->conf;
-	RadiusType msg_type = (RadiusType) sock_ctx;
+	RadiusType msg_type = (uintptr_t) sock_ctx;
 	int len, roundtrip;
 	unsigned char buf[RADIUS_MAX_MSG_LEN];
 	struct msghdr msghdr = {0};