staging: hv: Remove camel case variables in channel.c

Rename camel case variables in channel.c and changed them to
lowercase.
Signed-off-by: NHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: NHank Janssen <hjanssen@microsoft.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>