x86/intel_rdt: Fix a typo in Documentation

Example 3 contains a typo:

"C0" in "# echo C0 > p0/cpus" is wrong because it specifies core
6-7 instead of wanted core 4-7.

Correct this typo to avoid confusion.
Signed-off-by: NXiaochen Shen <xiaochen.shen@intel.com>
Acked-by: NFenghua Yu <fenghua.yu@intel.com>
Cc: vikas.shivappa@linux.intel.com
Cc: tony.luck@intel.com
Link: http://lkml.kernel.org/r/1493781356-24229-1-git-send-email-xiaochen.shen@intel.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Documentation/x86/intel_rdt_ui.txt

@@ -295,7 +295,7 @@ kernel and the tasks running there get 50% of the cache. They should
 also get 50% of memory bandwidth assuming that the cores 4-7 are SMT
 siblings and only the real time threads are scheduled on the cores 4-7.
 
-# echo C0 > p0/cpus
+# echo F0 > p0/cpus
 
 4) Locking between applications