drivers: intc: mchp_ecia_xec: Ensure correct device init order

We need to ensure that the XEC GIRQs are initialized after the
XEC ECIA device.  Right now we depend on the linker ordering
things correctly since everything is at INTC_INIT_PRIORITY
priority

Set the XEC GIRQs to 41 so the init priority is one more than
INTC_INIT_PRIORITY that is used by xec-ecia.

Signed-off-by: Kumar Gala <kumar.gala@intel.com>