zynqmp: FSBL->ATF handover

zynqmp: FSBL->ATF handover

Parse the parameter structure the FSBL populates, to populate the bl32
and bl33 image structures.

Cc: Sarat Chand Savitala <[email protected]>
Cc: [email protected]
Signed-off-by: Michal Simek <[email protected]>
[ SB
 - pass pointers to structs instead of structs
 - handle execution state parameter
 - populate bl32 SPSR
 - add documentation
 - query bootmode and consider missing handoff parameters an error when
   not in JTAG boot mode
]
Signed-off-by: Soren Brinkmann <[email protected]>