Fix @return Doxygen commands to be singular instead of plural.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12094 6f19259b-4bc3-4df7-8a09-765794883524

StdLib/BsdSocketLib/recv.c

@@ -26,12 +26,12 @@
   @param [in] s         Socket file descriptor returned from ::socket.
 
   @param [in] buffer    Address of a buffer to receive the data.
-  
+
   @param [in] length    Length of the buffer in bytes.
 
   @param [in] flags     Message control flags
 
-  @returns    ::recv returns the number of valid bytes in the buffer,
+  @return     ::recv returns the number of valid bytes in the buffer,
               zero if no data was received, and -1 when an error occurs.
               In the case of an error, errno contains more details.
 
@@ -45,7 +45,7 @@ recv (
   )
 {
   ssize_t BytesRead;
-  
+
   //
   //  Receive the data from the remote system
   //