riscv: add temporary riscv64_defconfig alias

This is to allow building of Xen without going through a separate
tiny64_defconfig build step, just like is possible for all other
architectures. Eventually the symlink will want replacing by,
presumably, an empty file just like other arches have.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>

diff --git a/xen/arch/riscv/configs/riscv64_defconfig b/xen/arch/riscv/configs/riscv64_defconfig
new file mode 120000 (symlink)
index 0000000..c3c97b4
--- /dev/null
+++ b/xen/arch/riscv/configs/riscv64_defconfig
@@ -0,0 +1 @@
+tiny64_defconfig
\ No newline at end of file