Update buildroot to 2021.02.1 (#1312)

Signed-off-by: Stefan Agner <stefan@agner.ch>

buildroot/package/pkg-kconfig.mk

@@ -117,7 +117,7 @@ $(2)_KCONFIG_STAMP_DOTCONFIG = .stamp_dotconfig
 $$($(2)_KCONFIG_FILE) $$($(2)_KCONFIG_FRAGMENT_FILES): | $(1)-patch
 	for f in $$($(2)_KCONFIG_FILE) $$($(2)_KCONFIG_FRAGMENT_FILES); do \
 		if [ ! -f "$$$${f}" ]; then \
-			printf "Kconfig fragment '%s' for '%s' does not exist\n" "$$$${f}" "$(1)"; \
+			printf "Kconfig file or fragment '%s' for '%s' does not exist\n" "$$$${f}" "$(1)"; \
 			exit 1; \
 		fi; \
 	done