[S] Change in coreboot[master]: payloads/Memtest86Plus: Update branch name from master to main

[9elements QA (Code Review)]

9elements QA has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/76100?usp=email )

Change subject: payloads/Memtest86Plus: Update branch name from master to main
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Patch Set 3:

Automatic boot test returned (PASS/FAIL/TOTAL): 8 / 8 / 16

FAIL: x86_32  "Hermes CFL" , build config PRODRIVE_HERMES_ 
     and payload TianoCore_UefiPayloadPkg : https://lava.9esec.io/r/170904
FAIL: x86_32  "Hermes CFL" , build config PRODRIVE_HERMES 
     and payload TianoCore_UefiPayloadPkg : https://lava.9esec.io/r/170902
FAIL: x86_32  "ThinkPad T500" , build config LENOVO_T500 
     and payload SeaBIOS : https://lava.9esec.io/r/170901
FAIL: x86_32  "HP Z220 SFF Workstation" , build config HP_Z220_SFF_WORKSTATION 
     and payload LinuxBoot_BB_kexec : https://lava.9esec.io/r/170900
FAIL: x86_64  "HP Compaq 8200 Elite SFF PC" , build config HP_COMPAQ_8200_ELITE_SFF_PC.X86_64 
     and payload TianoCore : https://lava.9esec.io/r/170899
FAIL: x86_64  "HP Compaq 8200 Elite SFF PC" , build config HP_COMPAQ_8200_ELITE_SFF_PC.X86_64 
     and payload SeaBIOS : https://lava.9esec.io/r/170898
FAIL: x86_32  "HP Compaq 8200 Elite SFF PC" , build config HP_COMPAQ_8200_ELITE_SFF_PC 
     and payload TianoCore : https://lava.9esec.io/r/170897
FAIL: x86_32  "HP Compaq 8200 Elite SFF PC" , build config HP_COMPAQ_8200_ELITE_SFF_PC 
     and payload SeaBIOS : https://lava.9esec.io/r/170896
PASS: x86_32  "QEMU x86 q35/ich9" , build config EMULATION_QEMU_X86_Q35_SMM_TSEG 
     and payload TianoCore : https://lava.9esec.io/r/170895
PASS: x86_32  "QEMU x86 q35/ich9" , build config EMULATION_QEMU_X86_Q35_SMM_TSEG 
     and payload SeaBIOS : https://lava.9esec.io/r/170894
PASS: x86_32  "QEMU x86 q35/ich9" , build config EMULATION_QEMU_X86_Q35 
     and payload TianoCore : https://lava.9esec.io/r/170893
PASS: x86_32  "QEMU x86 q35/ich9" , build config EMULATION_QEMU_X86_Q35 
     and payload SeaBIOS : https://lava.9esec.io/r/170892
PASS: x86_64  "QEMU x86 i440fx/piix4" , build config EMULATION_QEMU_X86_I440FX_X86_64 
     and payload SeaBIOS : https://lava.9esec.io/r/170891
PASS: x86_32  "QEMU x86 i440fx/piix4" , build config EMULATION_QEMU_X86_I440FX_ASAN 
     and payload SeaBIOS : https://lava.9esec.io/r/170890
PASS: x86_32  "QEMU x86 i440fx/piix4" , build config EMULATION_QEMU_X86_I440FX_ 
     and payload SeaBIOS : https://lava.9esec.io/r/170889
PASS: x86_32  "QEMU x86 i440fx/piix4" , build config EMULATION_QEMU_X86_I440FX 
     and payload SeaBIOS : https://lava.9esec.io/r/170888

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