1, Change name of PcdPlatformBootTimeoutDefault to PcdPlatformBootTimeout, now this...

1, Change name of PcdPlatformBootTimeoutDefault to PcdPlatformBootTimeout, now this PCD is *not* only hold default value of Bds timeout, but it is associated with a HII type PCD to hold persistent value for BDS timeout. Platform integrator will establish this mapping in platform DSC file.
2, Move PcdPlatformBootTimeout to IntelFrameworkModulePkg.
3, Remove BdsLibGetTimeout() interface from GenericBdsLib, because the PCD PcdPlatformBootTimeout will take care of persistent for time out value.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@7706 6f19259b-4bc3-4df7-8a09-765794883524