ARM: davinci: don't mark da850_register_cpufreq as __init

The mityomapl138_cpufreq_init and read_factory_config function in
board-mityomapl138.c are not __init functions and might be called
at a later stage, so da850_register_cpufreq must not be __init either.

Without this patch, building da8xx_omapl_defconfig results in:

WARNING: arch/arm/mach-davinci/built-in.o(.text+0x2eb4): Section mismatch in reference from the function read_factory_config() to the function .init.text:da850_register_cpufreq()
The function read_factory_config() references
the function __init da850_register_cpufreq().
This is often because read_factory_config lacks a __init
annotation or the annotation of da850_register_cpufreq is wrong.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Sekhar Nori <nsekhar@ti.com>
Cc: Kevin Hilman <khilman@ti.com>