Corrects the situation when it is impossible to use IOBUF with two
IOLOGIC elements at the same time - input and output.
Addresses https://github.com/YosysHQ/nextpnr/issues/1275
This is done by dividing one IOLOGIC Bel into two - input IOLOGIC and
output IOLOGIC plus checking for compatibility of the cells located
there.
At the moment, this check is simple and allows only the combination of
DDR and DDRC primitives.
Signed-off-by: YRabbit <rabbit@yrabbit.cyou>
4e8436a1fc