samsung: board: enable support of multiple board types

This change adds declaration of functions:
- set_board_type() - called at board_early_init_f()
- get_board_type() - called at checkboard()

For supporting multiple board types in a one config - it is welcome
to display the current board model. This is what get_board_type()
should return.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

include/samsung/misc.h

@@ -33,5 +33,9 @@ char *get_dfu_alt_system(void);
 char *get_dfu_alt_boot(void);
 void set_dfu_alt_info(void);
 #endif
+#ifdef CONFIG_BOARD_TYPES
+void set_board_type(void);
+const char *get_board_type(void);
+#endif
 
 #endif /* __SAMSUNG_MISC_COMMON_H__ */