platform/mellanox: Remove redundant 'NULL' check

Remove 'NULL' check for 'data->hpdev.client' in error flow of
mlxreg_lc_probe(). It cannot be 'NULL' at this point.

Fixes: b4b830a34d80 ("platform/mellanox: mlxreg-lc: Fix error flow and extend verbosity")
Reported-by: Dan Carpenter <[e-mail]>
Signed-off-by: Vadim Pasternak <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Hans de Goede <[e-mail]>
Signed-off-by: Hans de Goede <[e-mail]>

drivers/platform/mellanox/mlxreg-lc.c

···
 regcache_sync_fail:
 regmap_write_fail:
 devm_regmap_init_i2c_fail:
-	if (data->hpdev.client) {
-		i2c_unregister_device(data->hpdev.client);
-		data->hpdev.client = NULL;
-	}
+	i2c_unregister_device(data->hpdev.client);
+	data->hpdev.client = NULL;
 i2c_new_device_fail:
 	i2c_put_adapter(data->hpdev.adapter);
 	data->hpdev.adapter = NULL;