cpufreq: davinci: move configuration to include/linux/platform_data

The header containing the configuration structure for davinci cpufreq
driver lives in mach-davinci/include/mach/. This is fine for now but
if we want to make davinci part of the multi_v5 build, no code external
to mach-davinci should include machine-specific headers.

Move the configuration structure to include/linux/platform_data.

While we're at it: convert the GPL-2.0 boilerplate to a proper SPDX
license identifier.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Acked-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>