tests bsim: Remove unnecessary BT_TINYCRYPT_ECC selection

There is no need to select BT_TINYCRYPT_ECC as it will
be selected by default if the controller does not
provide BT_CTLR_ECDH[_SUPPORT].
But setting it in the prj.conf will break
for controllers that provide it,
as both host and controller will provide the same APIs.

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>