Some tweaks and cleanups for the DaVinci IRQ framework:

  - Don't bother storing a table of integers in SRAM and using it during
    IRQ dispatch.  Just do math on the IRQENTRY register to get the irq
    number with fewer and faster instructions, freeing that SRAM.

  - Provide a mechanism to use IRQ prioritization, and to let boards set it
    up as appropriate for the product at hand; there's a default mapping.
    (This approach to handling IRQ priorities, and the initial table, is
    modeled on how AT91 does this.)

  - Comment out declarations of bogus or reserved (per docs) IRQs.

  - Minor fixes to genirq setup:  only handle the AINTC irqs here; use
    genirq-style dispatcher names; and cleanup by merging both routines.

I'm certain the default irq priority table could stand tweaking.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Kevin Hilman <khilman@mvista.com>