Staging: lustre: obd_cksum.h: Remove unused cksum_types_supported_server

cksum_types_supported_server is defined in header file but not used
anywhere. Hence remove it.

Signed-off-by: Shraddha Barke <shraddha.6596@gmail.com>
Acked-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>