irqchip/mchp-eic: Fix error code in mchp_eic_domain_alloc()

irqchip/mchp-eic: Fix error code in mchp_eic_domain_alloc()

If irq_domain_translate_twocell() sets "hwirq" to >= MCHP_EIC_NIRQ (2) then
it results in an out of bounds access.

The code checks for invalid values, but doesn't set the error code.  Return
-EINVAL in that case, instead of returning success.

Fixes: 00fa3461c86d ("irqchip/mchp-eic: Add support for the Microchip EIC")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>
Link: https://patch.msgid.link/aTfHmOz6IBpTIPU5@stanley.mountain