arm: mach-omap2: load/start remoteproc IPU1/IPU2

First check the presence of the ipu firmware in the boot partition.
If present enable the ipu and the related clocks & then move
on to load the firmware and eventually start remoteproc IPU1/IPU2.

do_enable_clocks by default puts the clock domains into auto
which does not work well with reset. Hence adding do_enable_ipu_clocks
function.

Signed-off-by: Keerthy <j-keerthy@ti.com>
[Amjad: fix IPU1_LOAD_ADDR and compile warnings]
Signed-off-by: Amjad Ouled-Ameur <aouledameur@baylibre.com>