openssh: if we don't generate a dsa key we shouldn't look for it

The earlier commit ea119211b2 removed 'dsa' as one of the ssh_host_*_key
types that got generated.  Problem was that it didn't remove that key
as one of the paths that the server looks for by default.  As a
consequence, your log file might fill up with messages like:

    2017-06-01T15:43:07-06:00 openwrt sshd[31929]: error: Could not load host key: /etc/ssh/ssh_host_dsa_key

The patch is forunately trivial.  Don't set the path for the dsa
key file in the server configuration.

Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>

net/openssh/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=openssh
 PKG_VERSION:=7.5p1
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/ \
@@ -248,6 +248,7 @@ define Package/openssh-server/install
 	$(INSTALL_DIR) $(1)/etc/ssh
 	chmod 0700 $(1)/etc/ssh
 	$(INSTALL_DATA) $(PKG_INSTALL_DIR)/etc/ssh/sshd_config $(1)/etc/ssh/
+	sed -r -i 's,^#(HostKey /etc/ssh/ssh_host_(rsa|ecdsa|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)/usr/sbin