EXYNOS: LDS file move to common

smdk5250-uboot-spl.lds is moved to common folder, so that it can be reused.
It is renamed to exynos-uboot-spl.lds

Signed-off-by: Rajeshwari Shinde <rajeshwari.s@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>