Staging: hv: fix coding style issues in VmbusPacketFormat.h

Heh, volatiles, like that was a good idea...  Turns out they were not
even used, wierd stuff.

All clean except for the typedefs.

Cc: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>