zmx25: Convert to generic board

Boards need to select CONFIG_SYS_GENERIC_BOARD in order to prevent removal
from the project.

Cc: Matthias Weisser <weisserm@arcor.de>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>

include/configs/zmx25.h

@@ -15,6 +15,8 @@
 #define CONFIG_MX25
 #define CONFIG_SYS_TEXT_BASE		0xA0000000
 
+#define CONFIG_SYS_GENERIC_BOARD
+
 #define CONFIG_SYS_TIMER_RATE		32768
 #define CONFIG_SYS_TIMER_COUNTER	\
 	(&((struct gpt_regs *)IMX_GPT1_BASE)->counter)