Blackfin SPI Driver: Fix erroneous SPI Clock divisor calculation

Fix erroneous SPI Clock divisor calculation.  Make sure SPI_BAUD is always
>= 2.  Writing a value of 0 or 1 to the SPI_BAUD register disables the
serial clock.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/blackfin/include/asm/bfin5xx_spi.h b/arch/blackfin/include/asm/bfin5xx_spi.h
index 0292d58..ea2d24a 100644
--- a/arch/blackfin/include/asm/bfin5xx_spi.h
+++ b/arch/blackfin/include/asm/bfin5xx_spi.h
@@ -11,6 +11,8 @@
 #ifndef _SPI_CHANNEL_H_
 #define _SPI_CHANNEL_H_
 
+#define MIN_SPI_BAUD_VAL	2
+
 #define SPI_READ              0
 #define SPI_WRITE             1