KVM: x86: Replace IS_ERR() with IS_ERR_VALUE()

Avoid type casts that are needed for IS_ERR() and use
IS_ERR_VALUE() instead.

Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Link: https://lore.kernel.org/r/202211161718436948912@zte.com.cn


Signed-off-by: Sean Christopherson <seanjc@google.com>