mips: fix Section mismatch in reference

When building mips tinyconfig with clang the following error show up:

WARNING: modpost: vmlinux.o(.text+0x1940c): Section mismatch in reference from the function r4k_cache_init() to the function .init.text:loongson3_sc_init()
The function r4k_cache_init() references
the function __init loongson3_sc_init().
This is often because r4k_cache_init lacks a __init
annotation or the annotation of loongson3_sc_init is wrong.

Remove marked __init from function loongson3_sc_init(),
mips_sc_probe_cm3(), and mips_sc_probe().

Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>