irqchip/loongson-htpic: Remove redundant kfree operation

In the function htpic_of_init(), when kzalloc htpic fails, it should
return -ENOMEM directly, no need to execute "goto" to kfree.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1594087972-21715-2-git-send-email-yangtiezhu@loongson.cn