vdso/bits.h: Add BIT_ULL() for the sake of consistency

The minimization done in 3945ff37

 ("linux/bits.h: Extract common header
for vDSO") was required to isolate the VDSO build from the larger kernel
header impact.

The split added some inconsistency since BIT() and BIT_ULL() are now
defined in the different files which confuses unprepared reader.

Move BIT_ULL() to vdso/bits.h. No functional change.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20221128141003.77929-1-andriy.shevchenko@linux.intel.com