Provide static call to control IRQ preemption (called in CONFIG_PREEMPT)
so that we can override its behaviour when preempt= is overriden.

Since the default behaviour is full preemption, its call is
initialized to provide IRQ preemption when preempt= isn't passed.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210118141223.123667-8-frederic@kernel.org