spi: a3700: Remove a useless memset

Memory allocated by 'spi_alloc_master()' is already zeroed.
Remove a redundant memset.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/20200802175007.703995-1-christophe.jaillet@wanadoo.frSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-armada-3700.c

@@ -848,7 +848,6 @@ static int a3700_spi_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, master);
 
 	spi = spi_master_get_devdata(master);
-	memset(spi, 0, sizeof(struct a3700_spi));
 
 	spi->master = master;