mtd: spi-nor: Uniformize the return value in spi_nor_*_ready()

spi_nor_ready() returns 1 if ready, 0 if not ready and -errno on errors.
Do the same in all the spi_nor_*_ready() children.
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>

drivers/mtd/spi-nor/core.c

@@ -640,7 +640,7 @@ static int spi_nor_fsr_ready(struct spi_nor *nor)
 		return -EIO;
 	}
 
-	return nor->bouncebuf[0] & FSR_READY;
+	return !!(nor->bouncebuf[0] & FSR_READY);
 }
 
 /**