ArmPlatformPkg/Bds: initialize ConIn/ConOut/ErrOut before connecting terminals

In the following call tree:

  BdsEntry()
    DefineDefaultBootEntries()
      BdsConnectAllDrivers()
    InitializeConsole()
      set ConIn/ConOut/ErrOut

BdsConnectAllDrivers() connects SerialDxe -> TerminalDxe -> ConPlatformDxe
-> ConSplitterDxe before InitializeConsole has a chance to set ConIn /
ConOut / ErrOut. This causes ConPlatformDxe, at very first boot, to filter
out TerminalDxe's STI and STO from the set that ConSplitterDxe
multiplexes, leaving the system without a terminal console.

Reorder InitializeConsole() with DefineDefaultBootEntries(), so that the
variables be always set when DefineDefaultBootEntries() calls
BdsConnectAllDrivers().

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>