kallsyms: de-ifdef kallmodsyms

kallsyms: de-ifdef kallmodsyms

CONFIG_KALLMODSYMS is a bit ugly because of the burden of ifdefs.  It's
hard to remove them from scripts/kallsyms.c, but kernel/kallsyms.c doesn't
need any, since even when CONFIG_KALLMODSYMS is on it does not pull in any
extra build dependencies in and of itself: it just needs to arrange to not
create the kallmodsyms /proc node when the config option is turned off.
This will have the effect of disabling /proc/kallmodsyms when
CONFIG_KALLMODSYMS=n, without cluttering up the code with so many
ifdefs. (We still need one to populate the node in the first place.)

We also reverse the code motion we did earlier to make the other ifdefs
easier to insert.

Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Orabug: 21539840