package/xenomai: drop consecutive empty lines

Commit 4219c58c (xenomai: remove unnecessary autoreconf) introduced a
check-package warning:

1 warnings generated
package/xenomai/xenomai.mk:27: consecutive empty lines

https://gitlab.com/buildroot.org/buildroot/-/jobs/143155797

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/xenomai/xenomai.mk

@@ -24,7 +24,6 @@ XENOMAI_LICENSE_FILES = debian/copyright include/COPYING kernel/cobalt/COPYING \
 
 XENOMAI_DEPENDENCIES = host-pkgconf
 
-
 XENOMAI_INSTALL_STAGING = YES
 XENOMAI_INSTALL_TARGET_OPTS = DESTDIR=$(TARGET_DIR) install-user
 XENOMAI_INSTALL_STAGING_OPTS = DESTDIR=$(STAGING_DIR) install-user