kbuild: whitelist section mismatch in init/main.c

In init/main.c we have a reference from rest_init() to .init.text
which is intentional.
Rename the function 'init' to 'kernel_init' to make it a
kernel wide unique symbol and whitelist the reference.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

diff --cc init/main.c
Simple merge

diff --cc scripts/mod/modpost.c
Simple merge