package/mcelog: fix legal-info

README was renamed to README.md
https://git.kernel.org/pub/scm/utils/cpu/mce/mcelog.git/commit/README.md?id=2fda0091a0628480a08cbf6ebe309fcb83aeae34

Fixes
http://autobuild.buildroot.net/results/02b/02b897a843b995bf5bf3f993f48689870a551dd5/

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/mcelog/mcelog.mk

@@ -8,7 +8,7 @@ MCELOG_VERSION = v152
 MCELOG_SITE = $(BR2_KERNEL_MIRROR)/scm/utils/cpu/mce/mcelog.git
 MCELOG_SITE_METHOD = git
 MCELOG_LICENSE = GPL-2.0
-MCELOG_LICENSE_FILES = README
+MCELOG_LICENSE_FILES = README.md
 
 define MCELOG_BUILD_CMDS
 	$(MAKE) $(TARGET_CONFIGURE_OPTS) -C $(@D) all