Correct SPL use of NETDEVICES

This converts 1 usage of this option to the non-SPL form, since there is
no SPL_NETDEVICES defined in Kconfig

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/net/bootp.c b/net/bootp.c
index cae0419..8b1a4ae 100644
--- a/net/bootp.c
+++ b/net/bootp.c
@@ -1078,7 +1078,7 @@
 #endif	/* CONFIG_SYS_BOOTFILE_PREFIX */
 			dhcp_packet_process_options(bp);
 			if (CONFIG_IS_ENABLED(EFI_LOADER) &&
-			    CONFIG_IS_ENABLED(NETDEVICES))
+			    IS_ENABLED(CONFIG_NETDEVICES))
 				efi_net_set_dhcp_ack(pkt, len);
 
 #if defined(CONFIG_SERVERIP_FROM_PROXYDHCP)