Update kernel/.gitignore with new auto-generated files

Signed-off-by: S.Çağlar Onur <caglar@pardus.org.tr>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/.gitignore

@@ -3,3 +3,4 @@
 #
 config_data.h
 config_data.gz
+timeconst.h