integrate DDR cache patch for tf-a to solve boot hangs

Fix building for boards which don't provide external PHY clock

caused boot instability (board didn't boot every ~10 times)

integrate the proposals from ST to circumvent stop booting. DDR is expected
to be the reason for it

- adding patches for alpha2
- qspi nand patches are not ported to alpha2 yet

CONFIG_DM_VIDEO disabled. Also disabled CONFIG_SERIAL_RX_BUFFER else disabling video triggers u-boot bug

	CubeMX Version 4.99.1-C21

Now boots extlinux configuration directly. Previously it used a uboot script to do that

Enables configuration only if ip isn't already set by kernel commandline
(e.g. NFS boot)