grt: get correct min/max routing layers when checking pin layers
grt: get correct min/max routing layers when checking pin layers

Signed-off-by: Eder Monteiro <ef6fbc7d1828d63517989a504172fad247fa89f1@gmail.com>

The-OpenROAD-Project/OpenROAD,The-OpenROAD-Project/OpenROAD,QuantamHD/OpenROAD,QuantamHD/OpenROAD,The-OpenROAD-Project/OpenROAD,QuantamHD/OpenROAD,The-OpenROAD-Project/OpenROAD,The-OpenROAD-Project/OpenROAD,QuantamHD/OpenROAD,QuantamHD/OpenROAD