knfsd: nfsd4: simplify exp_pseudoroot arguments

We're passing three arguments to exp_pseudoroot, two of which are just fields
of the svc_rqst.  Soon we'll want to pass in a third field as well.  So let's
just give up and pass in the whole struct svc_rqst.

Also sneak in some minor style cleanups while we're at it.

Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>