[microTVM] Temporarily remove mps2_an521 from CI (#8927)
[microTVM] Temporarily remove mps2_an521 from CI (#8927)

Temporarily removing the mps2_an512 board from CI due to issue 8728.
Possibly all tests can fail on mps2_an512, so removing the board
instead of xfailing specific tests.

Signed-off-by: Gustavo Romero <9bcda9b045c05177cdce50eb6336ee47fa99123c@linaro.org>
Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,Laurawly/tvm-1,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,dmlc/tvm,dmlc/tvm,dmlc/tvm,Laurawly/tvm-1,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,dmlc/tvm