irqchip/csky: Return true/false (not 1/0) from bool functions

Return boolean values ("true" or "false") instead of 1 or 0 from bool
functions.

Signed-off-by: Haowen Bai <baihaowen@meizu.com>
Acked-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1647487284-30088-1-git-send-email-baihaowen@meizu.com