BeagleBoneBlackPkg: Remove ArmTrustedMonitorLibNull, RealtimeClockLib

Remove duplicates.

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

Booting from PrePi.

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

Depreciate local PrePi.

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

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

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

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