BeagleBoneBlackPkg: Use IntelFrameworkModulePkg BDS

Add IntelFrameworkModulePkg/Universal/BdsDxe/BdsDxe.inf and dependencies.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Varad Gautam <varadgautam@gmail.com>
BeagleBoneBlackPkg: Add SerialPortPoll to SerialPortLib

Enable SerialPortPoll to check if serial buffer contains data.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Varad Gautam <varadgautam@gmail.com>