rockchip: board: puma-rk3399: update .its file to use new features

rockchip: board: puma-rk3399: update .its file to use new features

This commit updates the .its file for the RK3399-Q7 to use the new
features and demonstrates how to use those:
 * it marks the ATF as the 'firmware'
 * it tracks the OS-type for U-Boot and ATF
 * it loads the PMU (M0) firmware to DRAM and records the location
   to /fit-images (where our ATF reads it from)

With the handoff of the next-stage FDT to ATF in place, we can now use
this to pass information about the load addresses and names of each
loadables to ATF: now we can load the M0 firmware into DRAM and avoid
overwriting parts of the SPL stage.  This is achieved by changing our
.its-file to use an available area of DRAM as the load-address.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>