EmbeddedPkg: Introduced a separate SerialPortExtLib library

Formerly only the header was defined and it was expecting the SerialPortExtLib
interface to be implemented by SerialPortLib if supported. This behaviour was
not conform to the EDK2 framework.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Olivier Martin <olivier.martin@arm.com>



git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14173 6f19259b-4bc3-4df7-8a09-765794883524
14 files changed