IntelFrameworkModulePkg: Modify IsaSerialDxe to follow driver rules

IsaSerialDxe creates child handles and wishes to retrieve the name for
those child controllers.

However, in the IsaSerialComponentNameGetControllerName() function, it
directly return EFI_UNSUPPORTED when ChildHandle != NULL.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17289 6f19259b-4bc3-4df7-8a09-765794883524