rx: Remove needless braces

Doing if ((a==b)) is unecessary. It's also potentially dangerous, as
that's the syntax required to do assignment within an if statement.
clang now issues warnings (errors in -Werror mode) when it encounters
these.

Remove pointless braces from the Unix CM to make clang happy.

Reviewed-on: http://gerrit.openafs.org/7088
Tested-by: Simon Wilkinson <simonxwilkinson@gmail.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit 5e107724f3661254cfdb693ae2d4d1c5238eba7d)

Change-Id: I99a04d9a2c547e34a3daca6f9e6714f6c7b76b9c
Reviewed-on: http://gerrit.openafs.org/10732
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Perry Ruiter <pruiter@sinenomine.net>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>