ShellPkg: Update Api from NetLibDetectMedia to NetLibDetectMediaWaitTimeout.

ShellPkg: Update Api from NetLibDetectMedia to NetLibDetectMediaWaitTimeout.

Since new Api NetLibDetectMediaWaitTimeout was involved to support connecting
state handling, and it is forward compatible. So apply this Api in ShellPkg.

V2:
   *Define time period in a macro instead of hard code.

Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Cc: Wu Jiaxin <jiaxin.wu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Wang Fan <fan.wang@intel.com>
Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>
Signed-off-by: fanwang2 <fan.wang@intel.com>