fix(zynqmp): modify function to have single return

This corrects the MISRA violation C2012-15.5:
A function should have a single point of exit at the end.
Introduced a temporary variable to store the return value to
ensure single return for the function.

Change-Id: Ibff3df16b4c591384467771bc7cb316f1773f1ea
Signed-off-by: Maheedhar Bollapalli <maheedharsai.bollapalli@amd.com>
9 files changed