sysklogd: fix redundant newline escape

Broken since 428f1e7e (sysklogd: install configuration file
unconditionally). Fixes:

package/sysklogd/sysklogd.mk:21: *** missing 'endef', unterminated 'define'.  Stop.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>