RISC-V: KVM: Drop the return value of kvm_riscv_vcpu_aia_init()

RISC-V: KVM: Drop the return value of kvm_riscv_vcpu_aia_init()

The kvm_riscv_vcpu_aia_init() does not return any failure so drop
the return value which is always zero.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Tested-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Nutty Liu <liujingqi@lanxincomputing.com>
Link: https://lore.kernel.org/r/20250618113532.471448-3-apatel@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>