OvmfPkg/PlatformBootManagerLib: Use ConvertDevicePathToText()

OvmfPkg/PlatformBootManagerLib: Use ConvertDevicePathToText()

The DevicePathToStr() function (in
"IntelFrameworkModulePkg/Library/GenericBdsLib/DevicePath.c") is a
simple wrapper around ConvertDevicePathToText().

DevicePathToStr() passes DisplayOnly=TRUE and AllowShortcuts=TRUE to
ConvertDevicePathToText(), whereas in this patch, both parameters are
flipped to FALSE.

The formatted devpaths are used only for debugging purposes, so this
change is safe.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>