spi: fsl_qspi: fix an error of using GENMASK

This commit fixes the change of below commit
"spi: fsl_qspi: Use GENMASK"
(sha1 :bad490a24212c068c5b718b9189f47ea4075d078)

Signed-off-by: Gong Qianyu <Qianyu.Gong@freescale.com>
Reviewed-by: Jagan Teki <jteki@openedev.com>

drivers/spi/fsl_qspi.c

@@ -25,7 +25,7 @@ DECLARE_GLOBAL_DATA_PTR;
 #define TX_BUFFER_SIZE		0x40
 #endif
 
-#define OFFSET_BITS_MASK	GENMASK(24, 0)
+#define OFFSET_BITS_MASK	GENMASK(23, 0)
 
 #define FLASH_STATUS_WEL	0x02