Omap35xxPkg, BeagleBoardPkg: Use Pcd for INTERRUPT_BASE

Omap35xxPkg, BeagleBoardPkg: Use Pcd for INTERRUPT_BASE

The base address for the interrupt controller is hard-coded in
Omap3530Interrupt.h, although Omap35xxPkg/InterruptDxe appears to
have initially intended to make use of PcdInterruptBaseAddress from
EmbeddedPkg. Move it to use said Pcd, and also declare use of it in
BeagleBoardLib, which makes a direct access.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>