spi: spi-mxc: add defines for clk inactive state for ECSPI

Provide define for the SCLK_CTL field of the config reg of ECSPI.
While at it, oder the defines to improve readability and make
adding more defines easier.

Signed-off-by: Markus Niebel <Markus.Niebel@tqs.de>
Reviewed-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>
diff --git a/arch/arm/include/asm/arch-mx5/imx-regs.h b/arch/arm/include/asm/arch-mx5/imx-regs.h
index 4955ccf..054c680 100644
--- a/arch/arm/include/asm/arch-mx5/imx-regs.h
+++ b/arch/arm/include/asm/arch-mx5/imx-regs.h
@@ -230,9 +230,10 @@
 #define MXC_CSPICTRL_CHAN	18
 
 /* Bit position inside CON register to be associated with SS */
-#define MXC_CSPICON_POL		4
-#define MXC_CSPICON_PHA		0
-#define MXC_CSPICON_SSPOL	12
+#define MXC_CSPICON_PHA		0  /* SCLK phase control */
+#define MXC_CSPICON_POL		4  /* SCLK polarity */
+#define MXC_CSPICON_SSPOL	12 /* SS polarity */
+#define MXC_CSPICON_CTL		20 /* inactive state of SCLK */
 #define MXC_SPI_BASE_ADDRESSES \
 	CSPI1_BASE_ADDR, \
 	CSPI2_BASE_ADDR, \