mfd: hi6421-pmic: Change license text to shorter form

Change license text to a shorter form of GPLv2.

Signed-off-by: Guodong Xu <guodong.xu@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
1 file changed