docs: marvell: armada: Update MARVELL_PLATFORM list and build instructions
docs: marvell: armada: Update MARVELL_PLATFORM list and build instructions

The supported MARVELL_PLATFORM list is updated to include the recently added
a80x0_puzzle platform (IEI Puzzle-M801).

Additionally building instructions are added for the GST ESPRESSObin-Ultra
board (1 GB, DDR4 RAM variant), which has been tested successfully and booted
TF-A on the board.

Signed-off-by: Luka Kovacic <ec14f1bdda93f5c7468eba8c178c78885521e3f3@sartura.hr>
Change-Id: Ie5724df27c1ee2e8f6a52664520579e872471e93

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