mm: swap: fix kerneldoc of swap_vma_readahead()

Fix W=1 compile warnings (invalid kerneldoc):

    mm/swap_state.c:742: warning: Function parameter or member 'fentry' not described in 'swap_vma_readahead'
    mm/swap_state.c:742: warning: Excess function parameter 'entry' description in 'swap_vma_readahead'

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200728171109.28687-2-krzk@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/swap_state.c

@@ -725,7 +725,7 @@ static void swap_ra_info(struct vm_fault *vmf,
 
 /**
  * swap_vma_readahead - swap in pages in hope we need them soon
- * @entry: swap entry of this memory
+ * @fentry: swap entry of this memory
  * @gfp_mask: memory allocation flags
  * @vmf: fault information
  *