linux-phytec-fsl

sysctl: the include of rcupdate.h is only needed in the kernel

Fixes this build-check error:

  include/linux/sysctl.h:28: included file 'linux/rcupdate.h' is not exported

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>