ArmVirtPkg/PlatformBootManagerLib: link against UefiBootManagerLib

ArmVirtPkg/PlatformBootManagerLib: link against UefiBootManagerLib

The general BDS helper functions are now provided by MdeModulePkg's
UefiBootManagerLib, and no longer by IntelFrameworkModulePkg's
GenericBdsLib.

This patch parallels OvmfPkg commit 2b23b8d45b62.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Ruiyu Ni <ruiyu.ni@Intel.com>