package/hackrf: add a comma between licenses

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit 4afa6fd8c1457dce95b830da3ad3b0d255ca1d09)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/hackrf/hackrf.mk

@@ -7,7 +7,7 @@
 HACKRF_VERSION = 2018.01.1
 HACKRF_SITE = https://github.com/mossmann/hackrf/releases/download/v$(HACKRF_VERSION)
 HACKRF_SOURCE = hackrf-$(HACKRF_VERSION).tar.xz
-HACKRF_LICENSE = GPL-2.0+ BSD-3-Clause
+HACKRF_LICENSE = GPL-2.0+, BSD-3-Clause
 HACKRF_LICENSE_FILES = COPYING
 HACKRF_DEPENDENCIES = fftw-single libusb
 HACKRF_SUBDIR = host