nohz: Fix old dynticks idle Kconfig backward compatibility
nohz: Fix old dynticks idle Kconfig backward compatibility

In order to enforce backward compatibility with older
config files, we want the new dynticks-idle Kconfig entry
to default its value to the one of the old CONFIG_NO_HZ symbol
if present.

Namely we want:

	config NO_HZ # old obsolete dynticks idle symbol
		bool

	config NO_HZ_IDLE # new dynticks idle symbol
		default NO_HZ

However Kconfig prevents this to work if the old symbol
is not visible. And this is currently the case because
NO_HZ lacks a title in order to show it in make oldconfig
and alike.

To fix this, bring a minimal title and help text to the
obsolete Kconfig entry that explains its purpose. This
makes the "defaulting" to work.

Reported-by: Ingo Molnar <9dbbbf0688fedc85ad4da37637f1a64b8c718ee2@kernel.org>
Signed-off-by: Frederic Weisbecker <e8a1bf9163cb25e93cfd6540f223b3872ea7ee55@gmail.com>
Cc: Chris Metcalf <074881f6f5da4d3b5278870ff234d1077ee622c0@tilera.com>
Cc: Christoph Lameter <ef3ecccf258fa062c5c6521a4887d40541963af7@linux.com>
Cc: Geoff Levand <c3918f39022407dee6a0056ceca9b1aa80e8e4ce@infradead.org>
Cc: Gilad Ben Yossef <27506c49d0aa0134c702962114d52970047df659@benyossef.com>
Cc: Hakan Akkan <3110d7decc6848bc68ee32ab65d10a43a57255c8@gmail.com>
Cc: Ingo Molnar <9dbbbf0688fedc85ad4da37637f1a64b8c718ee2@kernel.org>
Cc: Kevin Hilman <f9849b02abe18c1ece6bd40346458ed53f49d31b@linaro.org>
Cc: Li Zhong <22bc8bfd7eeb9886fe79aed380759aa078990d01@linux.vnet.ibm.com>
Cc: Paul E. McKenney <1e0ce936bb9b355d257bf5790d2513c3f28be22b@linux.vnet.ibm.com>
Cc: Paul Gortmaker <ae947f3c8df96e1dc851c5e3e5a930ce6d3f1f74@windriver.com>
Cc: Peter Zijlstra <3fddac958924aef220f202ca567388ddab3f14a8@infradead.org>
Cc: Steven Rostedt <43232e92d70cc7aa53504ad0397085ee47bad87f@goodmis.org>
Cc: Thomas Gleixner <00e4cf8f46a57000a44449bf9dd8cbbcc209fd2a@linutronix.de>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas