x86: fix 2 section mismatch warnings - find_and_reserve_crashkernel

WARNING: vmlinux.o(.text+0xcd1f): Section mismatch in reference from the function find_and_reserve_crashkernel() to the function .init.text:find_e820_area()
The function find_and_reserve_crashkernel() references
the function __init find_e820_area().
This is often because find_and_reserve_crashkernel lacks a __init
annotation or the annotation of find_e820_area is wrong.

WARNING: vmlinux.o(.text+0xcd38): Section mismatch in reference from the function find_and_reserve_crashkernel() to the function .init.text:reserve_bootmem_generic()
The function find_and_reserve_crashkernel() references
the function __init reserve_bootmem_generic().
This is often because find_and_reserve_crashkernel lacks a __init
annotation or the annotation of reserve_bootmem_generic is wrong.

find_and_reserve_crashkernel is called from __init function (reserve_crashkernel)
and calls 2 __init functions (find_e820_area, reserve_bootmem_generic),
so mark it __init

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>