irqchip/aspeed-i2c-ic: Fix irq_of_parse_and_map() return value

The irq_of_parse_and_map() returns 0 on failure, not a negative ERRNO.

Fixes: f48e699d ("irqchip/aspeed-i2c-ic: Add I2C IRQ controller for Aspeed")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220423094227.33148-1-krzysztof.kozlowski@linaro.org