RISC-V: KVM: Share APLIC and IMSIC defines with irqchip drivers

We have common APLIC and IMSIC headers available under
include/linux/irqchip/ directory which are used by APLIC
and IMSIC irqchip drivers. Let us replace the use of
kvm_aia_*.h headers with include/linux/irqchip/riscv-*.h
headers.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>