OvmfPkg: QemuVideoDxe: eliminate useless Private->HardwareNeedsStarting

OvmfPkg: QemuVideoDxe: eliminate useless Private->HardwareNeedsStarting

Currently, QemuVideoGraphicsOutputQueryMode() reports EFI_NOT_STARTED when
this boolean field is set.

However, QemuVideoGraphicsOutputQueryMode() is only available to callers
after the GOP interface has been installed. That in turn implies that the
following partial call tree has succeeded without errors:

  QemuVideoControllerDriverStart()
    QemuVideoGraphicsOutputConstructor()
      QemuVideoGraphicsOutputSetMode(... 0 ...)
        HardwareNeedsStarting = FALSE
    InstallMultipleProtocolInterfaces(... GOP ...)

That is, when QemuVideoGraphicsOutputQueryMode() is reached,
HardwareNeedsStarting is always FALSE.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15286 6f19259b-4bc3-4df7-8a09-765794883524