Spreadtrum UART console support

configname: CONFIG_SERIAL_SPRD_CONSOLE

Linux Kernel Configuration
└─>Device Drivers
└─>Character devices
└─>Serial drivers
└─>Spreadtrum UART console support
In linux kernel since version 4 (release Date: 2015-04-12)  
Support for early debug console using Spreadtrum's serial. This enables
the console before standard serial driver is probed. This is enabled
with "earlycon" on the kernel command line. The console is
enabled when early_param is processed.