cpuidle: pseries: Mark pseries_idle_proble() as __init

cpuidle: pseries: Mark pseries_idle_proble() as __init

After commit 7cbd631d4dec ("cpuidle: pseries: Fixup CEDE0 latency only
for POWER10 onwards"), pseries_idle_probe() is no longer inlined when
compiling with clang, which causes a modpost warning:

WARNING: modpost: vmlinux.o(.text+0xc86a54): Section mismatch in
reference from the function pseries_idle_probe() to the function
.init.text:fixup_cede0_latency()
The function pseries_idle_probe() references
the function __init fixup_cede0_latency().
This is often because pseries_idle_probe lacks a __init
annotation or the annotation of fixup_cede0_latency is wrong.

pseries_idle_probe() is a non-init function, which calls
fixup_cede0_latency(), which is an init function, explaining the
mismatch. pseries_idle_probe() is only called from
pseries_processor_idle_init(), which is an init function, so mark
pseries_idle_probe() as __init so there is no more warning.

Fixes: 959bd1db7443 ("cpuidle: pseries: Add function to parse extended CEDE records")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210803211547.1093820-1-nathan@kernel.org