x86 idle: remove 32-bit-only "no-hlt" parameter, hlt_works_ok flag

Remove 32-bit x86 a cmdline param "no-hlt",
and the cpuinfo_x86.hlt_works_ok that it sets.

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.

Indeed, hlt_works_ok was consulted in only 3 places.

First, in /proc/cpuinfo where "hlt_bug yes"
would be printed if and only if the user booted
the system with "no-hlt" -- as there was no other code
to set that flag.

Second, check_hlt() would not invoke halt() if "no-hlt"
were on the cmdline.

Third, it was consulted in stop_this_cpu(), which is invoked
by native_machine_halt()/reboot_interrupt()/smp_stop_nmi_callback() --
all cases where the machine is being shutdown/reset.
The flag was not consulted in the more frequently invoked
play_dead()/hlt_play_dead() used in processor offline and suspend.

Since Linux-3.0 there has been a run-time notice upon "no-hlt" invocations
indicating that it would be removed in 2012.

Signed-off-by: Len Brown <len.brown@intel.com>
Cc: x86@kernel.org

Documentation/kernel-parameters.txt

@@ -1881,10 +1881,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			wfi(ARM) instruction doesn't work correctly and not to
 			use it. This is also useful when using JTAG debugger.
 
-	no-hlt		[BUGS=X86-32] Tells the kernel that the hlt
-			instruction doesn't work correctly and not to
-			use it.
-
 	no_file_caps	Tells the kernel not to honor file capabilities.  The
 			only way then for a file to be executed with privilege
 			is to be setuid root or executed by root.