RZ/G2N clock support

modulename: r8a774b1-cpg-mssr.ko

configname: CONFIG_CLK_R8A774B1

Linux Kernel Configuration
└─>Device Drivers
└─>Common Clock Framework
└─>RZ/G2N clock support
In linux kernel since version 5.1 (release Date: 2019-05-05)  
source code:
drivers/clk/renesas/r8a774b1-cpg-mssr.c