Change in coreboot[master]: mb/google/cherry: Add DRAM calibration support

[Rex-BC Chen (Code Review)]

Attention is currently required from: Hung-Te Lin, Yu-Ping Wu.
Rex-BC Chen has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/54269 )

Change subject: mb/google/cherry: Add DRAM calibration support
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Patch Set 9:

(2 comments)

File src/mainboard/google/cherry/sdram_configs.c:

https://review.coreboot.org/c/coreboot/+/54269/comment/919e9ecd_3323a84f 
PS4, Line 8: Currently ddr_geometry and ddr_type are not used in Cherry.
> Amazing. I wonder if we can then readback the information on size, rank, channel, size, ... etc. […]

We can get all information after dram-k.
It needs some effort to implement this.
Is there any method we can pass these information from coreboot to kernel?

File src/mainboard/google/cherry/sdram_configs.c:

https://review.coreboot.org/c/coreboot/+/54269/comment/a6a5c514_a54972ed 
PS6, Line 7: 	/*
           : 	 * Currently ddr_geometry and ddr_type are not used in Cherry.
           : 	 * This function is declared for common dram init flow.
           : 	 */
           : 	static struct sdram_info params;
           : 
           : 	params.ddr_geometry = DDR_TYPE_2CH_2RK_6GB_3_3;
           : 	params.ddr_type = DDR_TYPE_EMCP;
           :
> s/dummy/placeholder

Done