misc: pci_endpoint_test: Cleanup extra 0 initialization

Initialization is not needed as memory is already set to 0 by devm_kzalloc.

Signed-off-by: Christian Bruel <christian.bruel@foss.st.com>
[mani: reworded description]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Link: https://patch.msgid.link/20250804170916.3212221-3-christian.bruel@foss.st.com