examples & TF-M: Default to AN552 and update TF-M

Following some changes in registers and memory layout, a new Corstone-
300 implementation AN552 becomes available and supercedes AN547.

Having recently added AN552 support to the HAL, we switch all examples
to use AN552 instead of AN547. No examples or CMake presets are provided
for AN547 anymore, because it requires one of the old FVPs none of which
has both TF-M and EMAC working.

TF-M has been bumped to an unreleased SHA1 which is the same revision
from which AN552 support in the HAL was imported. This is because AN552
support is not available in any TF-M releases yet. The signing script
has been modified due to a change in where secure image and bootloader
builds are located.

Now the CI uses FVP 11.16 whose model is AN552 and has working TF-M and
EMAC.

Signed-off-by: Lingkai Dong <lingkai.dong@arm.com>