tslib: use SPDX identifiers for licenses in use

[Peter: License is GPL-2.0+ / LGPL-2.1+]
Signed-off-by: Martin Kepplinger <martink@posteo.de>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

(cherry picked from commit 56ed4a1ef20aea9bbf46c8c17cb275e3173d5acf)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/tslib/tslib.mk

@@ -7,7 +7,7 @@
 TSLIB_VERSION = 1.5
 TSLIB_SITE = https://github.com/kergoth/tslib/releases/download/$(TSLIB_VERSION)
 TSLIB_SOURCE = tslib-$(TSLIB_VERSION).tar.xz
-TSLIB_LICENSE = GPL, LGPL
+TSLIB_LICENSE = GPL-2.0+ (programs), LGPL-2.1+ (libraries)
 TSLIB_LICENSE_FILES = COPYING
 
 TSLIB_AUTORECONF = YES