kernel: fix earlycon by keeping __earlycon_table

Somewhere between 4.4 and 4.9 there was a change that made
OF_EARLYCON_DECLARE adding entries to the __earlycon_table instead of
__earlycon_of_table. We need to keep this table as well.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

target/linux/generic/patches-4.9/721-phy_packets.patch

@@ -28,7 +28,7 @@
  	const struct header_ops *header_ops;
  
  	unsigned int		flags;
-@@ -1779,6 +1782,10 @@ struct net_device {
+@@ -1779,6 +1786,10 @@ struct net_device {
  	struct mpls_dev __rcu	*mpls_ptr;
  #endif