ManageabilityPkg: Replace __FUNCTION__ with __func__

Signed-off-by: Abner Chang <abner.chang@amd.com>
Cc: Isaac Oram <isaac.w.oram@intel.com>
Cc: Abdul Lateef Attar <abdattar@amd.com>
Cc: Nickle Wang <nicklew@nvidia.com>
Cc: Tinh Nguyen <tinhnguyen@os.amperecomputing.com>
Reviewed-by: Nickle Wang <nicklew@nvidia.com>
Reviewed-by: Abdul Lateef Attar <abdattar@amd.com>