freevxfs: lookup: fix function params kernel-doc

Correct the function parameter kernel-doc notation to prevent warnings:

vxfs_lookup.c:192: warning: Function parameter or member 'ctx' not described in 'vxfs_readdir'
vxfs_lookup.c:192: warning: Excess function parameter 'retp' description in 'vxfs_readdir'
vxfs_lookup.c:192: warning: Excess function parameter 'filler' description in 'vxfs_readdir'

Link: https://lkml.kernel.org/r/20231207212035.25345-3-rdunlap@infradead.org


Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>