samsung: board/misc: check returned pointer for get_board_type() calls

samsung: board/misc: check returned pointer for get_board_type() calls

The function get_board_type() is called in two places by common code,
but the returned pointer was never check.

This commit adds checking the returned pointer, before use it.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Anand Moon <linux.amoon@gmail.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>