x86/Kconfig: Specify idle=poll instead of no-hlt

Commit 27be4570 ("x86 idle: remove 32-bit-only "no-hlt" parameter,
hlt_works_ok flag") removed no-hlt, but CONFIG_APM still refers to
it. Suggest "idle=poll" instead, based on the commit message:

> If a user wants to avoid HLT, then "idle=poll"
> is much more useful, as it avoids invocation of HLT
> in idle, while "no-hlt" failed to do so.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/20220713160840.1577569-1-steve@sk2.org