KVM: x86: hyper-v: Use common code for hypercall userspace exit

Remove duplicate code to exit to userspace for hyper-v hypercalls and
use a common place to exit.

No functional change intended.

Signed-off-by: Vipin Sharma <vipinsh@google.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20221212183720.4062037-9-vipinsh@google.com


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