drivers/mmc/mv_sdhci.c: Fix build warning

Fix:
mv_sdhci.c: In function 'mv_sdh_init':
mv_sdhci.c:47:22: warning: the comparison will always
evaluate as 'true' for the address of 'mv_sdhci_writeb'
will never be NULL [-Waddress]

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Cc: Lei Wen <leiwen@marvell.com>
Cc: Andy Fleming <afleming@freescale.com>
Acked-by: Lei Wen <leiwen@marvell.com>

drivers/mmc/mv_sdhci.c

@@ -44,7 +44,6 @@ int mv_sdh_init(u32 regbase, u32 max_clk, u32 min_clk, u32 quirks)
 	host->quirks = quirks;
 #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
 	memset(&mv_ops, 0, sizeof(struct sdhci_ops));
-	if (mv_sdhci_writeb != NULL)
 	mv_ops.write_b = mv_sdhci_writeb;
 	host->ops = &mv_ops;
 #endif