openssh: add UCI support

* update init script to handle sshd UCI by generating config file
  and passing that config file to the sshd daemon
* add a default sshd config
* add uci-default script that tries to migrate dropbear config
  and authorized_keys file to sshd

Signed-off-by: Mohd Husaam Mehdi <husaam.mehdi@iopsys.eu>

net/openssh/Makefile

@@ -232,10 +232,14 @@ define Package/openssh-server/install
 	sed -r -i 's,^#(HostKey /etc/ssh/ssh_host_(rsa|ed25519)_key)$$$$,\1,' $(1)/etc/ssh/sshd_config
 	$(INSTALL_DIR) $(1)/etc/init.d
 	$(INSTALL_BIN) ./files/sshd.init $(1)/etc/init.d/sshd
+	$(INSTALL_DIR) $(1)/etc/config
+	$(INSTALL_BIN) ./files/sshd.config $(1)/etc/config/sshd
 	$(INSTALL_DIR) $(1)/lib/preinit
 	$(INSTALL_BIN) ./files/sshd.failsafe $(1)/lib/preinit/99_10_failsafe_sshd
 	$(INSTALL_DIR) $(1)/usr/sbin
 	$(INSTALL_BIN) $(PKG_INSTALL_DIR)/usr/sbin/sshd $(1)/usr/sbin/
+	$(INSTALL_DIR) $(1)/etc/uci-defaults
+	$(INSTALL_DATA) ./files/sshd.ucidefault $(1)/etc/uci-defaults/99-generate-sshd-config
 endef
 
 define Package/openssh-server-pam/install

net/openssh/files/sshd.config

@@ -0,0 +1,6 @@
+config sshd
+	option enable '1'
+	option Port '22'
+	option RootLogin '1'
+	option PasswordAuth '1'
+	option RootPasswordAuth '1'