ARM: S3C24XX: Add SPDX license identifiers

Replace GPL license statements with SPDX license identifiers (GPL-2.0
and GPL-2.0+).  The h1940-bluetooth.c was licensed under GPL-1.0.  This
also adds GPL-2.0 to few files lacking license statement.

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