drm/amd/display: Fix false BAD_FREE warning from Coverity

This is an attempt to fix false warning raised by Coverity
via multiple CID's.

Addresses-Coverity-ID: 1487412 ("Free of address-of expression")
Cc: Wesley Chalmers <Wesley.Chalmers@amd.com>

Reviewed-by: Wesley Chalmers <wesley.chalmers@amd.com>
Acked-by: Mikita Lipski <mikita.lipski@amd.com>
Signed-off-by: Anson Jacob <Anson.Jacob@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_link_dpcd.c

@@ -176,12 +176,15 @@ static void dpcd_reduce_address_range(
 		uint8_t * const reduced_data,
 		const uint32_t reduced_size)
 {
-	const uint32_t reduced_end_address = END_ADDRESS(reduced_address, reduced_size);
-	const uint32_t extended_end_address = END_ADDRESS(extended_address, extended_size);
 	const uint32_t offset = reduced_address - extended_address;
 
-	if (extended_end_address == reduced_end_address && extended_address == reduced_address)
-		return; /* extended and reduced address ranges point to the same data */
+	/*
+	 * If the address is same, address was not extended.
+	 * So we do not need to free any memory.
+	 * The data is in original buffer(reduced_data).
+	 */
+	if (extended_data == reduced_data)
+		return;
 
 	memcpy(&extended_data[offset], reduced_data, reduced_size);
 	kfree(extended_data);