fix(zynqmp): add external declaration

This corrects the MISRA violation C2012-8.4:
A compatible declaration shall be visible when an object or
function with external linkage is defined.

Change-Id: I0e554972c24b70abd5b563639482f267cd4e1b5e
Signed-off-by: Nithin G <[email protected]>
Signed-off-by: Maheedhar Bollapalli <[email protected]>
4 files changed