misc: poky/LICENSE has changed.. reference a hopefully more stable file

Only reference the COPYING.MIT as it is unlikely to change in
the next upgrade.
diff --git a/recipes-osmocom/tasks/task-core-standalone-osmo-sdk-target.bb b/recipes-osmocom/tasks/task-core-standalone-osmo-sdk-target.bb
index 6eb5d21..41a95b1 100644
--- a/recipes-osmocom/tasks/task-core-standalone-osmo-sdk-target.bb
+++ b/recipes-osmocom/tasks/task-core-standalone-osmo-sdk-target.bb
@@ -4,8 +4,7 @@
 
 DESCRIPTION = "Software Development Kit for Osmocom devices"
 LICENSE = "MIT"
-LIC_FILES_CHKSUM = "file://${COREBASE}/LICENSE;md5=3f40d7994397109285ec7b81fdeb3b58 \
-                    file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420"
+LIC_FILES_CHKSUM = "file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420"
 PR = "r5"
 
 ALLOW_EMPTY_${PN} = "1"