Cortina Gemini OF-based physical memory map handling

configname: CONFIG_MTD_PHYSMAP_GEMINI

Linux Kernel Configuration
└─>Device Drivers
└─>Memory Technology Device (MTD) support
└─>Mapping drivers for chip access
└─>Cortina Gemini OF-based physical memory map handling
In linux kernel since version 5 (release Date: 2019-03-03)  
This provides some extra DT physmap parsing for the Gemini
platforms, some detection and setting up parallel mode on the
external interface.