Drivers: hv: remove unused variable from channel_mgmt.c

The variables guidtype, guidinstance and initiate are initialized but
never used otherwise, so remove the unused variables.

dpatch engine is used to auto generate this patch.
(https://github.com/weiyj/dpatch

)

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>