x86/cpu: Rename cpu_data.x86_mask to cpu_data.x86_stepping

x86_mask is a confusing name which is hard to associate with the
processor's stepping.

Additionally, correct an indent issue in lib/cpu.c.

Signed-off-by: Jia Zhang <qianyue.zj@alibaba-inc.com>
[ Updated it to more recent kernels. ]
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bp@alien8.de
Cc: tony.luck@intel.com
Link: http://lkml.kernel.org/r/1514771530-70829-1-git-send-email-qianyue.zj@alibaba-inc.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/events/intel/p6.c

@@ -234,7 +234,7 @@ static __initconst const struct x86_pmu p6_pmu = {
 
 static __init void p6_pmu_rdpmc_quirk(void)
 {
-	if (boot_cpu_data.x86_mask < 9) {
+	if (boot_cpu_data.x86_stepping < 9) {
 		/*
 		 * PPro erratum 26; fixed in stepping 9 and above.
 		 */