brppt1: Fix SPL boot stage

Commit 6337d53f ("arm: dts: sync am33xx with Linux 5.9-rc7") syncs
the am335x device tree with the latest linux kernel am335x device tree.
That causes problems with device tree in SPL stage.
To fix the issues CONFIG_SPL_OF_TRANSLATE must be set to handle the
synced bus addresses correctly.
A custom U-Boot device tree is also needed since the SPL build removes
bus properties from bus nodes which are not explicitly marked with the
u-boot,dm-spl or u-boot,dm-pre-reloc flag. Therefore all parent buses of
the in the SPL needed devices must be marked with u-boot,dm-pre-reloc.
Also since there is no driver for "ti,sysc" compatible property in SPL
the buses marked with this compatible string must also be marked with
compatible = "simple-bus" to make the underlying devices visible in
SPL. Otherwise the matching device drivers aren't found and the uclass
drivers are dropped.

Signed-off-by: Bernhard Messerklinger <bernhard.messerklinger@br-automation.com>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>