fix(versal2): typecast expressions to match data type

This corrects the MISRA violation C2012-10.4:
Both operands of an operator in which the usual arithmetic
conversions are performed shall have the same essential type
category.
The condition is explicitly checked against 0U, appending 'U' and
typecasting for unsigned comparison.

Change-Id: Ia352e3cf261b52777c1c431701e1e6c3be9cd279
Signed-off-by: Maheedhar Bollapalli <maheedharsai.bollapalli@amd.com>
diff --git a/plat/amd/versal2/scmi.c b/plat/amd/versal2/scmi.c
index 6375df3..fa0b2ca 100644
--- a/plat/amd/versal2/scmi.c
+++ b/plat/amd/versal2/scmi.c
@@ -293,7 +293,7 @@
 		return SCMI_NOT_FOUND;
 	}
 
-	if (start_idx > 0) {
+	if (start_idx > 0U) {
 		return SCMI_OUT_OF_RANGE;
 	}