x86_32: apic/summit_32, fix section mismatch

Remove __init section placement for some functions/data, so that
we don't get section mismatch warnings.

Also make inline function instead of empty setup_summit macro.

[v2]
One of them was not caught by
DEBUG_SECTION_MISMATCH=y
magic. Fix it.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: H. Peter Anvin <hpa@zytor.com>