Syntax bug bdy_r = bdy_r in nemo_bdy_gen_c.py

[b-barton]

In line 105 of nemo_bdy_gen_c.py there is a syntax bug. At present it is:
bdy_r = bdy_r = np.tile(np.arange(0, rw), (bdy_i.shape[0], 1))

and should be changed to:
bdy_r = np.tile(np.arange(0, rw), (bdy_i.shape[0], 1))