brltty: add license

brltty 5.5 is licensed under GPL-2.0+ with exceptions in LGPL-2.1+ for
data and client side as specified in README so add this information in
BRLTTY_LICENSE, update BRLTTY_LICENSE_FILES and add hash for README

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit ecf832704bd360f40dc0c898d48c3ea2e8b7fb53)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/brltty/brltty.hash

@@ -1,3 +1,4 @@
 sha256 4ebf1df5922df0efccac4795f5bd1c514fc850348c34d9ec0868e2798b565a36 brltty-5.5.tar.xz
 sha256 91df39d1816bfb17a4dda2d3d2c83b1f6f2d38d53e53e41e8f97ad5ac46a0cad LICENSE-GPL
 sha256 d80c9d084ebfb50ea1ed91bfbc2410d6ce542097a32c43b00781b83adcb8c77f LICENSE-LGPL
+sha256 6ba58188449642de8adefd7adabb436185792c5c51a4b5d04650423c2151dc50 README

package/brltty/brltty.mk

@@ -9,7 +9,8 @@ BRLTTY_SOURCE = brltty-$(BRLTTY_VERSION).tar.xz
 BRLTTY_SITE = http://brltty.com/archive
 BRLTTY_INSTALL_STAGING_OPTS = INSTALL_ROOT=$(STAGING_DIR) install
 BRLTTY_INSTALL_TARGET_OPTS = INSTALL_ROOT=$(TARGET_DIR) install
-BRLTTY_LICENSE_FILES = LICENSE-GPL LICENSE-LGPL
+BRLTTY_LICENSE = GPL-2.0+, LGPL-2.1+ (data, client side)
+BRLTTY_LICENSE_FILES = LICENSE-GPL LICENSE-LGPL README
 
 BRLTTY_DEPENDENCIES = $(TARGET_NLS_DEPENDENCIES) host-autoconf host-pkgconf \
 	$(if $(BR2_PACKAGE_AT_SPI2_CORE),at-spi2-core)