x86/hvm: address a violation of MISRA C:2012 Rule 11.8

The xen sources contain violations of MISRA C:2012 Rule 11.8 whose
headline states:
"A conversion shall not remove any const, volatile or _Atomic qualification
from the type pointed to by a pointer".

Remove unnecessary cast.
from is a const-qualified pointer to void and the function hvm_copy_to_guest_linear
requires a const void* type argument, therefore the cast to void* is not necessary.

No functional change.

Signed-off-by: Maria Celeste Cesario  <[email protected]>
Signed-off-by: Simone Ballarin  <[email protected]>
Reviewed-by: Jan Beulich <[email protected]>
Reviewed-by: Stefano Stabellini <[email protected]>

xen/arch/x86/hvm/hvm.c

@@ -3462,7 +3462,7 @@ unsigned int copy_to_user_hvm(void *to, const void *from, unsigned int len)
         return 0;
     }
 
-    rc = hvm_copy_to_guest_linear((unsigned long)to, (void *)from, len, 0, NULL);
+    rc = hvm_copy_to_guest_linear((unsigned long)to, from, len, 0, NULL);
     return rc ? len : 0; /* fake a copy_to_user() return code */
 }