It might be as simple as that:
import torch
import torch.nn as nn

class NormedConv( nn.Conv2d ):

    def normalize( self ):
        with torch.no_grad():
            for f in range( 0, self.weight.shape[0] ):
                s                    = torch.sum( self.weight[f,:,:,:] )
                self.weight[f,:,:,:] = torch.div( self.weight[f,:,:,:], s )