mm/swapfile.c: fix swap_count comment about nonexistent SWAP_HAS_CONT

mm/swapfile.c: fix swap_count comment about nonexistent SWAP_HAS_CONT

Commit 570a335b8e22 ("swap_info: swap count continuations") introduces
COUNT_CONTINUED but refers to it incorrectly as SWAP_HAS_CONT in a
comment in swap_count.  Fix it.

Link: http://lkml.kernel.org/r/[email protected]
Fixes: 570a335b8e22 ("swap_info: swap count continuations")
Signed-off-by: Daniel Jordan <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>