Staging: hv: remove STRUCT_PACKED and STRUCT_ALIGNED defines

Use the correct __attribute__((packed)) one if it's really needed.

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