Looks like the toolchain doesn't recognize TLBVADDR. Masked it in crt.S temporarily.

crt.S:88: Error: unrecognized keyword/register name `rcsr r24,TLBVADDR'
crt.S:98: Error: unrecognized keyword/register name `rcsr r24,TLBVADDR'
crt.S:108: Error: unrecognized keyword/register name `rcsr r24,TLBVADDR'

oks like
Toolchain doesn't seems to recognize mmu related stuff. Masking TESTCASES += test_mmu.elf