package/sysdig: fix legal-info

Fix typo: SYSDIG_LICENSE_FILE -> SYSDIG_LICENSE_FILES
added by commit ea86757e51cf424566f79896335d31d15b89d0d9

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/sysdig/sysdig.mk

@@ -7,7 +7,7 @@
 SYSDIG_VERSION = 0.29.2
 SYSDIG_SITE = $(call github,draios,sysdig,$(SYSDIG_VERSION))
 SYSDIG_LICENSE = Apache-2.0
-SYSDIG_LICENSE_FILE = COPYING
+SYSDIG_LICENSE_FILES = COPYING
 SYSDIG_CPE_ID_VENDOR = sysdig
 SYSDIG_CONF_OPTS = \
 	-DENABLE_DKMS=OFF \