fix(zynqmp): with DEBUG=1 move bl31 to DDR range

fix(zynqmp): with DEBUG=1 move bl31 to DDR range

Due to size constraints in OCM memory range keeping the bl31 with
DEBUG=1 overlaps with the memory range from other Firmware thus
affecting the bootflow on target.
bl31 binary can not be placed in OCM memory range when built with
DEBUG=1.
With DEBUG=1, by default bl31 is moved to DDR memory range
0x1000-0x7FFFF.
The user can provide a custom DDR memory range during build time using
the build parameters ZYNQMP_ATF_MEM_BASE and ZYNQMP_ATF_MEM_SIZE.

Change-Id: I167d5eadbae7c6d3ec9b32f494b0b1a819bea5b0
Signed-off-by: Akshay Belsare <akshay.belsare@amd.com>