freevxfs: immed: fix kernel-doc param name

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

vxfs_immed.c:32: warning: Function parameter or member 'fp' not described in 'vxfs_immed_read_folio'
vxfs_immed.c:32: warning: Excess function parameter 'file' description in 'vxfs_immed_read_folio'

Link: https://lkml.kernel.org/r/20231207212035.25345-2-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>