package/hackrf: drop unrecognized option

Drop BUILD_HACKRF_TOOLS which has never been recognized since the
addition of the package in commit
29b7cc88f401dcc69a085be5af067851f896da58

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/hackrf/hackrf.mk

@@ -13,8 +13,6 @@ HACKRF_DEPENDENCIES = fftw-single libusb
 HACKRF_SUBDIR = host
 HACKRF_INSTALL_STAGING = YES
 
-HACKRF_CONF_OPTS += -DBUILD_HACKRF_TOOLS=ON
-
 ifeq ($(BR2_PACKAGE_HAS_UDEV),y)
 HACKRF_CONF_OPTS += \
 	-DINSTALL_UDEV_RULES=ON \