wireshark: fix static build

Don't give a path in --with-pcap option otherwise PCAP_CONFIG won't be
used (see AC_WIRESHARK_PCAP_CHECK in acinclude.m4) to retrieve pcap
static dependencies such as -lnl-3 and as a result pcap detection will
fail

Fixes:
 - http://autobuild.buildroot.org/results/084354a33825cf4e723e0a9f1e9656ad2a212a15

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit fecf82a1668c5cfbe6ebec985ce60a5526bcf35c)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/wireshark/wireshark.mk

@@ -24,7 +24,7 @@ WIRESHARK_CONF_OPTS = \
 	--without-nghttp2 \
 	--without-snappy \
 	--with-libsmi=no \
-	--with-pcap=$(STAGING_DIR)/usr
+	--with-pcap=yes
 
 # wireshark GUI options
 ifeq ($(BR2_PACKAGE_LIBGTK3),y)