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>
Reviewed-by: Maurice Ma <maurice.ma@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17143 6f19259b-4bc3-4df7-8a09-765794883524