OvmfPkg/XenHypercallLib: Fix naming of AArch64

Fix path to follow naming convention of "AArch64", and allow the path
in "Maintainers.txt" to work as expected.

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3982
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>

OvmfPkg/Library/XenHypercallLib/AArch64/Hypercall.S

@@ -0,0 +1,20 @@
+
+/** @file
+  AArch64 implementation of XenHypercall2
+
+  Copyright (C) 2014, Linaro Ltd.
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <IndustryStandard/Xen/arch-arm/xen.h>
+
+  .text
+  .global   ASM_PFX(XenHypercall2)
+ASM_PFX(XenHypercall2):
+  mov     x16, x0
+  mov     x0, x1
+  mov     x1, x2
+  hvc     #XEN_HYPERCALL_TAG
+  ret