Change in coreboot[master]: src/mainboard/emulation/qemu-power9/*: add QEMU POWER9 mainboard

[Arthur Heymans (Code Review)]

Attention is currently required from: Sergii Dmytruk, Ron Minnich, Timothy Pearson.
Arthur Heymans has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/57079 )

Change subject: src/mainboard/emulation/qemu-power9/*: add QEMU POWER9 mainboard
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Patch Set 11: Code-Review+1

(2 comments)

File src/mainboard/emulation/qemu-power9/board.fmd:

https://review.coreboot.org/c/coreboot/+/57079/comment/907413e8_8cf63a7b 
PS11, Line 12: FLASH@0 CONFIG_ROM_SIZE {
             : 	BIOS@0 CONFIG_ROM_SIZE {
             : 		BOOTBLOCK 128K
             : 		FMAP 0x200
             : 		COREBOOT(CBFS)
             : 	}
             : }
This looks identical to util/cbfstool/default.fmd. Use that?

File src/mainboard/emulation/qemu-power9/cbmem.c:

https://review.coreboot.org/c/coreboot/+/57079/comment/7769b1a8_d9973e7c 
PS11, Line 9: (1ULL << 32) - 1048576
4ULL * GiB - 1 * MiB