log_check / tainted_check failed in ubuntu_boot because of warnings found on G-riscv

[Po-Hsu Lin]

Found on Groovy RISCV 5.8.0-21-generic

kernel_tainted test failed with:
  ERROR: kernel tainted flag != 0: 512

This is because of the warning messages in dmesg:
 Scanning for pattern "kernel: \[ *\d+\.\d+\] WARNING:.*"
 Pattern found. Matching lines as follows:
 kernel: [ 14.848036] WARNING: CPU: 3 PID: 1 at arch/riscv/mm/ptdump.c:200 note_page+0x24c/0x252
 kernel: [ 14.625316] WARNING: CPU: 1 PID: 1 at arch/riscv/mm/ptdump.c:200 note_page+0x24c/0x252
 kernel: [ 16.949300] WARNING: CPU: 0 PID: 1 at arch/riscv/mm/ptdump.c:200 note_page+0x24c/0x252
 kernel: [ 13.263889] WARNING: CPU: 6 PID: 1 at arch/riscv/mm/ptdump.c:200 note_page+0x24c/0x252