APLIC's domaincfg.IE bit and idelivery registers affect only interrupt delivery

[jhauser-us]

For an APLIC, clarify that an interrupt domain's global IE bit in register domaincfg affects only whether interrupts are delivered to harts (by wire or by MSI), nothing else. The value of domaincfg.IE has no effect on the following:

• the visible values of the interrupt-enable and interrupt-pending bits of active interrupt sources;
• the values of IDC registers, including idelivery, topi, and claimi.

Likewise, an IDC structure's idelivery register affects only whether interrupts are delivered to the relevant hart; it has no effect on other IDC registers, including topi and claimi.