ARM: samsung: Rename Samsung and Exynos to lowercase

Fix up inconsistent usage of upper and lowercase letters in "Samsung"
and "Exynos" names.

"SAMSUNG" and "EXYNOS" are not abbreviations but regular trademarked
names.  Therefore they should be written with lowercase letters starting
with capital letter.

The lowercase "Exynos" name is promoted by its manufacturer Samsung
Electronics Co., Ltd., in advertisement materials and on website.

Although advertisement materials usually use uppercase "SAMSUNG", the
lowercase version is used in all legal aspects (e.g. on Wikipedia and in
privacy/legal statements on
https://www.samsung.com/semiconductor/privacy-global/

).

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>