fix(zynqmp): fix DT reserved allocated size

BL31_LIMIT is not size but reserved node reg property contains base
address and size that's why BL31_LIMIT - BL31_BASE + 1 is correct size
of reseved space for BL31.
Also update warning message to cover that it is for BL31.

Change-Id: I53f53d2170eb873f758f9ba250d54f57f0b562b4
Signed-off-by: Michal Simek <michal.simek@amd.com>
1 file changed