SFI: fix section mismatch warnings in sfi_core.c

The function sfi_map_memory/sfi_unmap_memory uses
early_ioremap/early_iounmap respectively, which refers to a __init
function.  And function sfi_check_table also refers to a __init function
sfi_verify_table.  Since the references are valid, so use __ref to get rid
of the warnings.

 We were warned by the following warnings:

  LD      vmlinux.o
  MODPOST vmlinux.o
WARNING: vmlinux.o(.text+0xb6ba3a): Section mismatch in reference from
the function sfi_map_memory() to the function
.init.text:early_ioremap()
The function sfi_map_memory() references
the function __init early_ioremap().
This is often because sfi_map_memory lacks a __init
annotation or the annotation of early_ioremap is wrong.

WARNING: vmlinux.o(.text+0xb6bab6): Section mismatch in reference from
the function sfi_unmap_memory() to the function
.init.text:early_iounmap()
The function sfi_unmap_memory() references
the function __init early_iounmap().
This is often because sfi_unmap_memory lacks a __init
annotation or the annotation of early_iounmap is wrong.

WARNING: vmlinux.o(.text+0xb6be30): Section mismatch in reference from
the function sfi_check_table() to the function
.init.text:sfi_verify_table()
The function sfi_check_table() references
the function __init sfi_verify_table().
This is often because sfi_check_table lacks a __init
annotation or the annotation of sfi_verify_table is wrong.

Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>