xen/riscv: use some asm-generic headers

Some headers are the same as asm-generic verions of them
so use them instead of arch-specific headers.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/riscv/include/asm/Makefile

@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0-only
+generic-y += altp2m.h
+generic-y += device.h
+generic-y += div64.h
+generic-y += hardirq.h
+generic-y += hypercall.h
+generic-y += iocap.h
+generic-y += paging.h
+generic-y += percpu.h
+generic-y += random.h
+generic-y += softirq.h
+generic-y += vm_event.h