core188: Ship u-boot for aarch64

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

diff --git a/config/rootfiles/core/188/filelists/aarch64/u-boot b/config/rootfiles/core/188/filelists/aarch64/u-boot
new file mode 120000 (symlink)
index 0000000..2a16bdb
--- /dev/null
+++ b/config/rootfiles/core/188/filelists/aarch64/u-boot
@@ -0,0 +1 @@
+../../../../common/aarch64/u-boot
\ No newline at end of file