S25FL1 FLASH driver: Fix return value from the bwrite() method

ChangeLog

@@ -10881,7 +10881,7 @@
 	  device (2015-08-24).
 	* networking:  Correct return value from psock_tcp_accept().  From
 	  SaeHie Park (2015-08-25).
-	* drivers/mtd/st25fl1.c: Add a driver for ST25L1*K QuadSPI parts
+	* drivers/mtd/s25fl1.c: Add a driver for ST25L1*K QuadSPI parts
 	  (2015-08-25).
 	* include/nuttx/spi/qspi.h:  Develop a new interface for QSPI, at
 	  least the way that QSPI is implemented on the SAMV71.  Originally
@@ -11071,4 +11071,6 @@
 	* arch/arm/src/samv7:  Add a call to can_txready() to the MCAN driver
 	  (2015-11-03).
 	* arch/arm/src/samv7:  Add MPU and protected build support (2015-11-06).
-
+	* arch/arm/src/samv7:  The QSPI FLASH driver is now functional.  This
+	  driver operates in the memory-mapped, Serial Memory Mode (SMM)
+	  (2015-11-07).

drivers/mtd/st25fl1.c

@@ -1289,7 +1289,7 @@ static ssize_t st25fl1_bwrite(FAR struct mtd_dev_s *dev, off_t startblock,
 
   st25fl1_unlock(priv->qspi);
 
-  return ret;
+  return ret < 0 ? ret : nblocks;
 }
 
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