handler_addr is a virtual address passed to efi_call_virt_pointer.
While x86 currently type cast it into the pointer in it's arch specific
arch_efi_call_virt() implementation, ARM64 is restrictive for right
reasons.

Convert the handler_addr type from u64 to void pointer.
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>