xilinx: firmware: Move dcache handling directly to pmufw load config

Core function should make sure that data is stored properly that's why move
cache operations directly to zynqmp_pmufw_load_config_object() to be able
to call it from other functions.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/8c92edd3650ce34a3cfd1c1e4e9103980830b1fa.1637236800.git.michal.simek@xilinx.com