mtd: m25p80: add debugging trace in sst_write

Add a DEBUG(MTD_DEBUG_LEVEL2, ..) trace at beginning of sst_write() function as
it is done in m25p80_write() function.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/devices/m25p80.c

@@ -497,6 +497,10 @@ static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,
 	size_t actual;
 	int cmd_sz, ret;
 
+	DEBUG(MTD_DEBUG_LEVEL2, "%s: %s %s 0x%08x, len %zd\n",
+			dev_name(&flash->spi->dev), __func__, "to",
+			(u32)to, len);
+
 	*retlen = 0;
 
 	/* sanity checks */