SPI: mxc_spi: replace fixed offsets with structures

This patch cleans driver code replacing all accesses
to registers with fixed offsets with a corresponding
structure.

Signed-off-by: Stefano Babic <sbabic@denx.de>
diff --git a/arch/arm/include/asm/arch-mx31/mx31-regs.h b/arch/arm/include/asm/arch-mx31/mx31-regs.h
index 46ed47c..105f7d8 100644
--- a/arch/arm/include/asm/arch-mx31/mx31-regs.h
+++ b/arch/arm/include/asm/arch-mx31/mx31-regs.h
@@ -64,6 +64,17 @@
 	u32	gpio_psr;
 };
 
+struct cspi_regs {
+	u32 rxdata;
+	u32 txdata;
+	u32 ctrl;
+	u32 intr;
+	u32 dma;
+	u32 stat;
+	u32 period;
+	u32 test;
+};
+
 #define IOMUX_PADNUM_MASK	0x1ff
 #define IOMUX_PIN(gpionum, padnum) ((padnum) & IOMUX_PADNUM_MASK)