cpumask: Make cpu_{online,possible,present,active}() inline

Prepare for addition of another mask. Primarily a code movement to
avoid having to create more #ifdef, but while there, convert
everything with an argument to an inline function.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20210310150109.045447765@infradead.org