MdeModulePkg EhciDxe: Extract new EhciInsertAsyncIntTransfer function

MdeModulePkg EhciDxe: Extract new EhciInsertAsyncIntTransfer function

V3:
Match function parameter name and description between
EhciSched.c and EhciSched.h.

V2:
Add the missing "gBS->FreePool (Data);".

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1274

Extract new EhciInsertAsyncIntTransfer function from
EhcAsyncInterruptTransfer.

It is code preparation for following patch,
no essential functional change.

Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Hao Wu <hao.a.wu@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Hao Wu <hao.a.wu@intel.com>