powerpc/pseries: Always inline functions called from cpuidle

Code in the idle path is not allowed to be instrumented because RCU is
disabled, see commit 0e985e9d ("cpuidle: Add comments about
noinstr/__cpuidle usage").

Force inlining of the inline functions called from cpuidle, to ensure
they are not emitted out-of-line and then available for tracing.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230406144535.3786008-4-mpe@ellerman.id.au