tools: hv: fcopy: set 'error' in case an unknown operation was requested

tools: hv: fcopy: set 'error' in case an unknown operation was requested

commit c2d68afba86d1ff01e7300c68bc16a9234dcd8e9 upstream.

'error' variable is left uninitialized in case we see an unknown operation.
As we don't immediately return and proceed to pwrite() we need to set it
to something, HV_E_FAIL sounds good enough.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>