orangefs: remove redundant assignment to variable buffer_index

The variable buffer_index is being initialized however this is never
read and later it is being reassigned to a new value. The initialization
is redundant and hence can be removed.

Addresses-Coverity: ("Unused Value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>