stingray: fix coverity reported issues on brcm platform

fix coverity reported issues
1. uninitialized var,
2. check for negative val on unsigned variable

Signed-off-by: Sheetal Tigadoli <sheetal.tigadoli@broadcom.com>
Change-Id: I28b7517135ba6c1ba0df04f0c73189cf84ba89e6
diff --git a/plat/brcm/board/stingray/src/paxb.c b/plat/brcm/board/stingray/src/paxb.c
index 28065f0..89f76d0 100644
--- a/plat/brcm/board/stingray/src/paxb.c
+++ b/plat/brcm/board/stingray/src/paxb.c
@@ -485,7 +485,7 @@
  */
 static int pcie_cores_init(void)
 {
-	int ret;
+	int ret = 0;
 	uint32_t core_idx;
 
 	if (paxb->pipemux_init) {