CorebootModulePkg: Remove unused static functions to prevent gcc build fail

The gcc build will fail with -Werror=unused-function when a compilation
unit defines a static function but never calls it.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Scott Duplichan <scott@notabs.org>
---

Index: CorebootModulePkg/Library/CbParseLib/CbParseLib.c
===================================================================
--- CorebootModulePkg/Library/CbParseLib/CbParseLib.c	(revision 17108)
+++ CorebootModulePkg/Library/CbParseLib/CbParseLib.c	(working copy)
@@ -31,16 +31,6 @@
   return (((UINT64) val.hi) << 32) | val.lo;
 }
 
-static const char *cb_mb_vendor_string(const struct cb_mainboard *cbm)
-{
-  return (char *)(cbm->strings + cbm->vendor_idx);
-}
-
-static const char *cb_mb_part_string(const struct cb_mainboard *cbm)
-{
-  return (char *)(cbm->strings + cbm->part_number_idx);
-}
-
 UINT16
 CbCheckSum16 (
   IN UINT16   *Buffer,