Change in coreboot[master]: mb: remove duplicated Make code for spd.bin generation

[9elements QA (Code Review)]

9elements QA has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/44774 )

Change subject: mb: remove duplicated Make code for spd.bin generation
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Patch Set 9:

Automatic boot test returned (PASS/FAIL/TOTAL): 7/1/8
"QEMU x86 q35/ich9" (x86_32) using payload TianoCore : SUCCESS : https://lava.9esec.io/r/17896
"QEMU x86 q35/ich9" (x86_32) using payload SeaBIOS : SUCCESS : https://lava.9esec.io/r/17895
"QEMU x86 i440fx/piix4" (x86_64) using payload SeaBIOS : FAIL : https://lava.9esec.io/r/17894
"QEMU x86 i440fx/piix4" (x86_32) using payload SeaBIOS : SUCCESS : https://lava.9esec.io/r/17893
"QEMU AArch64" using payload LinuxBoot_u-root_kexec : SUCCESS : https://lava.9esec.io/r/17892
"HP Z220 SFF Workstation" (x86_32) using payload LinuxBoot_BusyBox_kexec : SUCCESS : https://lava.9esec.io/r/17899
"HP Compaq 8200 Elite SFF PC" (x86_32) using payload TianoCore : SUCCESS : https://lava.9esec.io/r/17898
"HP Compaq 8200 Elite SFF PC" (x86_32) using payload SeaBIOS : SUCCESS : https://lava.9esec.io/r/17897

Please note: This test is under development and might not be accurate at all!