IB/ipath: Fix some sparse warnings about shadowed symbols

There are a few places in the ipath driver where a variable is
re-declared within a block where it is already in scope.  Most of these
extra declarations can simply be removed, since the variable from the
outer scope is used in a way so that it does not need to keep its
variable across the block with the re-declaration.

Signed-off-by: Roland Dreier <rolandd@cisco.com>