init/version-timestamp.c: remove unneeded #include <linux/version.h>

The kbuild test robot detected this by 'make versioncheck'.

Fixes: 2df8220c ("kbuild: build init/built-in.a just once")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

init/version-timestamp.c

@@ -2,7 +2,6 @@
 
 #include <generated/compile.h>
 #include <generated/utsrelease.h>
-#include <linux/version.h>
 #include <linux/proc_ns.h>
 #include <linux/refcount.h>
 #include <linux/uts.h>