staging/lustre: Remove unused OBD_VMALLOC

These macros are not used anymore, so let's remove them,
also __OBD_VMALLOC_VEROBSE and OBD_CPT_VMALLOC

Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>