x86/irq/32: Change some static functions to bool

The return values of these functions is 0/1, but they use an int
type instead of bool:

  check_stack_overflow()
  execute_on_irq_stack()

Change the type of these function to bool and adjust their return
values and affected helper variables.

[ mingo: Rewrote the changelog ]

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250303155446.112769-5-ubizjak@gmail.com