boards: holyiot_yj16019: Remove counter from supported

The supported field is used by sanitycheck to select which tests will be
run on a particular board. The issue with the counter drivers, and in
particular on nRF ICs, is that the timer peripherals are disabled by
default and need to be enabled on a per-board basis inside a .conf file.
Since this board doesn't have a .conf file in
tests/drivers/counter/counter_basic_api/boards/ the test cannot be run
on this board.

Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>