libshout: fix typo

Fix error:
  package/libshout/libshout.mk:28: *** Package error: use LIBSHOUT_CONF_OPTS instead of LIBSHOUT_CONF_OPT. Please fix your .mk file.  Stop.

Signed-off-by: Jérôme Pouiller <jezz@sysmic.org>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libshout/libshout.mk

@@ -19,7 +19,7 @@ LIBSHOUT_CONF_OPTS += --disable-theora
 endif
 
 ifeq ($(BR2_PACKAGE_SPEEX),y)
-LIBSHOUT_CONF_OPT += --enable-speex
+LIBSHOUT_CONF_OPTS += --enable-speex
 LIBSHOUT_DEPENDENCIES += speex
 else
 LIBSHOUT_CONF_OPTS += --disable-speex