cpufreq: s3c64xx: remove incorrect __init annotation

s3c64xx_cpufreq_config_regulator is incorrectly annotated
as __init, since the caller is also not init:

WARNING: vmlinux.o(.text+0x92fe1c): Section mismatch in reference from the function s3c64xx_cpufreq_driver_init() to the function .init.text:s3c64xx_cpufreq_config_regulator()

With modern gcc versions, the function gets inline, so we don't
see the warning, this only happens with gcc-4.6 and older.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>