zynqmp: Revise memory configuration options

Drop the current configuration options for selecting the location of
the ATF and TSP (ZYNQMP_ATF_LOCATION, ZYNQMP_TSP_RAM_LOCATION).
The new configuration provides one default setup (ATF in OCM,
BL32 in DRAM). Additionally, the new configuration options
 - ZYNQMP_ATF_MEM_BASE
 - ZYNQMP_ATF_MEM_SIZE
 - ZYNQMP_BL32_MEM_BASE
 - ZYNQMP_BL32_MEM_SIZE
can be used to freely configure the memory locations used for ATF and
secure payload.

Also, allow setting the BL33 entry point via PRELOADED_BL33_BASE.

Cc: petalinux-dev@xilinx.com
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Acked-by: Alistair Francis <alistair.francis@xilinx.com>