OMAP hwmod: add names to module MPU IRQ lines

Replace the existing u8 array of module MPU IRQ lines with a struct
that includes a name - similar to the existing struct
omap_hwmod_dma_info.  Device drivers can then use
platform_get_resource_byname() to retrieve specific IRQs without nasty
dependencies on array ordering.

Thanks to Benoît Cousson <b-cousson@ti.com> and Kevin Hilman
<khilman@deeprootsystems.com> for feedback on this approach.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Benoît Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>