staging: hv: Convert camel cased struct fields in ring_buffer.h to lower cases

staging: hv: Convert camel cased struct fields in ring_buffer.h to lower cases

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