package/mender: Fix incorrectly named service file

Many of the mender CLI commands use systemctl commands to get information about
the daemon, such as the PID (IE: systemctl show -p MainPID mender-client).
As seen above, these commands expect the service file to be named
"mender-client" instead of "mender."

As such, in the current state, running a forced update check in the CLI will
result in the following error:
failed to force updateCheck: could not find the PID of the mender daemon.

Changing the name of mender.service to mender-client.service fixes the issue.

Signed-off-by: Adam Duskett <Aduskett@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/mender/mender.mk

@@ -77,8 +77,8 @@ endef
 MENDER_POST_INSTALL_TARGET_HOOKS += MENDER_INSTALL_CONFIG_FILES
 
 define MENDER_INSTALL_INIT_SYSTEMD
-	$(INSTALL) -D -m 0644 $(MENDER_PKGDIR)/mender.service \
-		$(TARGET_DIR)/usr/lib/systemd/system/mender.service
+	$(INSTALL) -D -m 0644 $(MENDER_PKGDIR)/mender-client.service \
+		$(TARGET_DIR)/usr/lib/systemd/system/mender-client.service
 endef
 
 define MENDER_INSTALL_INIT_SYSV