Clean up a little:
 * Place brackets around variables in macros
 * Correctly exit the loop when we have found the irq handler
 * Fix the build when DEBUG is enabled
 * Add a KASSERT to check arm_ipi_pic is set when adding an ipi
 * Remove an unneeded ';'
 * Use OF_node_from_xref to translate the xref
Merge to r276034