x86: clean up vget_cycles()

Impact: remove unused variable

I forgot to remove the now unused "cycles_t cycles" parameter from
vget_cycles() - which triggers build warnings as tsc.h is included
in a number of files.

Remove it.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/include/asm/tsc.h

@@ -34,8 +34,6 @@ static inline cycles_t get_cycles(void)
 
 static __always_inline cycles_t vget_cycles(void)
 {
-	cycles_t cycles;
-
 	/*
 	 * We only do VDSOs on TSC capable CPUs, so this shouldnt
 	 * access boot_cpu_data (which is not VDSO-safe):