x86: fix 2 section mismatch warnings - map_high()

WARNING: vmlinux.o(.text+0x14cf8): Section mismatch in reference from the function map_high() to the function .init.text:init_extra_mapping_uc()
The function map_high() references
the function __init init_extra_mapping_uc().
This is often because map_high lacks a __init
annotation or the annotation of init_extra_mapping_uc is wrong.

WARNING: vmlinux.o(.text+0x14d05): Section mismatch in reference from the function map_high() to the function .init.text:init_extra_mapping_wb()
The function map_high() references
the function __init init_extra_mapping_wb().
This is often because map_high lacks a __init
annotation or the annotation of init_extra_mapping_wb is wrong.

map_high is called only from __init functions (map_*_high)
and calls 2 __init_functions (init_extra_mapping_*)

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