ice40: Add error for bad PACKAGE_PIN connections
ice40: Add error for bad PACKAGE_PIN connections

Signed-off-by: David Shah <4be9b043912c80de45ffb490ebd07e45bc0fcd34@gmail.com>

SymbiFlow/nextpnr,SymbiFlow/nextpnr,YosysHQ/nextpnr,SymbiFlow/nextpnr,YosysHQ/nextpnr,YosysHQ/nextpnr,YosysHQ/nextpnr,SymbiFlow/nextpnr