x86 idle: Fix mwait deprecation warning message

Fix:

  arch/x86/kernel/process.c:645:1: warning: unknown escape sequence '\i'

due to missing escape backslash, introduced by this commit:

  5d4c47e0: x86 idle: deprecate mwait_idle() and "idle=mwait" cmdline param
Signed-off-by: Borislav Petkov <bp@alien8.de>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1306748286-24701-1-git-send-email-bp@alien8.deSigned-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/process.c

@@ -642,7 +642,7 @@ static int __init idle_setup(char *str)
 		boot_option_idle_override = IDLE_POLL;
 	} else if (!strcmp(str, "mwait")) {
 		boot_option_idle_override = IDLE_FORCE_MWAIT;
-		WARN_ONCE(1, "\idle=mwait\" will be removed in 2012\"\n");
+		WARN_ONCE(1, "\"idle=mwait\" will be removed in 2012\"\n");
 	} else if (!strcmp(str, "halt")) {
 		/*
 		 * When the boot option of idle=halt is added, halt is