allwinner: A64: Limit FDT checks to reduce code size
allwinner: A64: Limit FDT checks to reduce code size

The upcoming refactoring to support the new H616 SoCs will push the A64
build over the edge, by using more than the 48KB of SRAM available.

To reduce the code size, set some libfdt options that aim to reduce
sanity checks (for saving code space):
- ASSUME_LATEST: only allow v17 DTBs (as created by dtc)
- ASSUME_NO_ROLLBACK: don't prepare for failed DT additions
- ASSUME_LIBFDT_ORDER: assume sane ordering, as done by dtc

Change-Id: I12c93ec09e7587c5ae71e54947f817c32ce5fd6d
Signed-off-by: Andre Przywara <94eb15b8f54b8e37c3f8d338296201be47dc5c3e@arm.com>

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware