mx35pdk: Convert to generic board

Boards need to select CONFIG_SYS_GENERIC_BOARD in order to
prevent removal from the project.
Signed-off-by: NStefano Babic <sbabic@denx.de>

include/configs/mx35pdk.h

@@ -19,6 +19,7 @@
 #define CONFIG_MX35
 
 #define CONFIG_DISPLAY_CPUINFO
+#define CONFIG_SYS_GENERIC_BOARD
 
 /* Set TEXT at the beginning of the NOR flash */
 #define CONFIG_SYS_TEXT_BASE	0xA0000000