package/psplash: add license file details

Signed-off-by: Pierre-Jean Texier <pjtexier@koncepto.io>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/psplash/psplash.hash

@@ -1,2 +1,3 @@
 # Locally computed
 sha256 aaddb20ef892dfb03d4e046cc634159bbcdfe555f7291652dde2b7d4cf491289  psplash-5b3c1cc28f5abdc2c33830150b48b278cc4f7bca.tar.gz
+sha256 f9c375a1be4a41f7b70301dd83c91cb89e41567478859b77eef375a52d782505  COPYING

package/psplash/psplash.mk

@@ -7,6 +7,7 @@
 PSPLASH_VERSION = 5b3c1cc28f5abdc2c33830150b48b278cc4f7bca
 PSPLASH_SITE = git://git.yoctoproject.org/psplash
 PSPLASH_LICENSE = GPL-2.0+
+PSPLASH_LICENSE_FILES = COPYING
 PSPLASH_AUTORECONF = YES
 
 define PSPLASH_INSTALL_INIT_SYSTEMD