spi: stm32: switch to SPDX identifier

Adopt the SPDX license identifier headers to ease license compliance
management.

Signed-off-by: Cezary Gapinski <cezary.gapinski@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
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Cezary Gapinski 2018-12-24 23:00:27 +01:00 • committed by Mark Brown
commit d57a984ff7
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