config_utils: Fix new line rstrip

Bug: 514305790
Test: Build DDK and observe no Kconfig warnings
Change-Id: I2f151cef2a2bffffc3da14ac6bb04c384551b65a
(cherry picked from commit 93f02f3fbb577a76e2f5cd8c38023435ec979d65)

build/kernel

diff --git a/build/kernel b/build/kernel
index 6524d52..f71dbd3 160000
--- a/build/kernel
+++ b/build/kernel
@@ -1 +1 @@
-Subproject commit 6524d522479e9c95ee529a8d117e6c8e79a6608d
+Subproject commit f71dbd37ecb1a45fadbcce80d1beeb5fb1833166