arm: omap2plus: move NAND_BLOCK_SIZE out of boards

Several boards defining mtd partitions also defined NAND_BLOCK_SIZE as
SZ_128K. Move the define to common-board-devices.h

This removes multiple defines of NAND_BLOCK_SIZE.

Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>
[tony@atomide.com: updated comments]
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/board-omap3touchbook.c

@@ -56,8 +56,6 @@
 
 #include <asm/setup.h>
 
-#define NAND_BLOCK_SIZE		SZ_128K
-
 #define OMAP3_AC_GPIO		136
 #define OMAP3_TS_GPIO		162
 #define TB_BL_PWM_TIMER		9