virt: acrn: Correct type casting of argument of copy_from_user()

hsm.c:336:50: warning: incorrect type in argument 2 (different address spaces)
hsm.c:336:50:    expected void const [noderef] __user *from
hsm.c:336:50:    got void *

This patch fixes above sparse warning.

Fixes: 3d679d5a

 ("virt: acrn: Introduce interfaces to query C-states and P-states allowed by hypervisor")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Link: https://lore.kernel.org/r/20210310153708.17451-1-shuo.a.liu@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>