mimic: fix legal info

Name of license file is 'COPYING'.

Fixes:
  http://autobuild.buildroot.net/results/846/846b42d484e8d3e261eb3699a485d589f6bbab62

Signed-off-by: Rahul Bedarkar <rahul.bedarkar@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/mimic/mimic.mk

@@ -7,7 +7,7 @@
 MIMIC_VERSION = 1.1.0
 MIMIC_SITE = $(call github,MycroftAI,mimic,$(MIMIC_VERSION))
 MIMIC_LICENSE = MIT
-MIMIC_LICENSE_FILES = LICENSE
+MIMIC_LICENSE_FILES = COPYING
 
 MIMIC_DEPENDENCIES = host-pkgconf