mm: keep kabi compatibility of may_expand_vm() etc

mm: keep kabi compatibility of may_expand_vm() etc

One of the previous patches:

  mm: rework virtual memory accounting

has modifications on the prototype of functions like may_expand_vm() and the
shared_vm field of mm struct, which actually break the compatibility of kabi.

In order to keep kabi compatibility intact, this patch changed the related
function prototype back and renamed the data_vm back to shared_vm.

Orabug: 30145754
Signed-off-by: Tong Chen <tong.c.chen@oracle.com>
Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>