board:samsung: move checkboard to common file

The checkboard function's implementation is common for all
DT supporting boards and should be placed in the board common file.

Signed-off-by: Piotr Wilczek <p.wilczek@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Chander Kashyap <k.chander@samsung.com>
Cc: Rajeshwari S Shinde <rajeshwari.s@samsung.com>
Cc: Amar <amarendra.xt@samsung.com>

Acked-by: Rajeshwari Shinde <rajeshwari.s@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>