NetworkPkg: UefiPxeBcDxe: Remove the redundant code.

The function PxeBcFreeBootFileOption that is never called
have been removed.

Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Siyuan Fu <siyuan.fu@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1064
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Songpeng Li <songpeng.li@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jiaxin Wu <jiaxin.wu@intel.com>

NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.h

@@ -116,16 +116,6 @@ typedef struct {
 } PXEBC_DHCP6_PACKET_CACHE;
 
 
-/**
-  Free all the nodes in the boot file list.
-
-  @param[in]  Head            The pointer to the head of the list.
-
-**/
-VOID
-PxeBcFreeBootFileOption (
-  IN LIST_ENTRY               *Head
-  );
 
 
 /**