CRIS v10: kernel/time.c needs to include linux/vmstat.h to compile

This fixes compile error when nr_free_pages() from linux/swap.h
expands to global_page_state(NR_FREE_PAGES), but linux/vmstat.h isn't
included to declare global_page_state().

Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Mikael Starvik <mikael.starvik@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>