NetworkPkg: Replace the internal function with exposed one

This patch is used to replace the internal function with
the exposed one defined in NetLib.h.

Cc: Hegde Nagaraj P <nagaraj-p.hegde@hpe.com>
Cc: El-Haj-Mahmoud Samer <samer.el-haj-mahmoud@hpe.com>
Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>
Reviewed-by: Hegde Nagaraj P <nagaraj-p.hegde@hpe.com>
Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>

NetworkPkg/DnsDxe/DnsImpl.h

@@ -87,7 +87,6 @@ extern EFI_DNS6_PROTOCOL             mDns6Protocol;
 
 #define DNS_DEFAULT_TIMEOUT      2
 #define DNS_DEFAULT_RETRY        3
-#define DNS_DEFAULT_BLKSIZE      512
 
 #define DNS_TIME_TO_GETMAP       5
 
@@ -556,24 +555,6 @@ AddDns6ServerIp (
   IN EFI_IPv6_ADDRESS           ServerIp
   );
 
-/**
-  Fill QName for IP querying. QName is a domain name represented as 
-  a sequence of labels, where each label consists of a length octet 
-  followed by that number of octets. The domain name terminates with 
-  the zero length octet for the null label of the root.
-
-  @param  HostName          Queried HostName    
-
-  @retval NULL      Failed to fill QName.
-  @return           QName filled successfully.
-  
-**/ 
-CHAR8 *
-EFIAPI
-DnsFillinQNameForQueryIp (
-  IN  CHAR16              *HostName
-  );
-
 /**
   Find out whether the response is valid or invalid.