staging: lustre: split error handling code into multiple labels

Instead of using a switch-case statement to find out what kind of error
has just happened, split error handling logic into multiple labels and
jump right into the appropriate label to do the error handling. This way
it is easier to follow different code paths. It also looks easy on the
eyes.

Additionally silences the following coccinelle warning:

drivers/staging/lustre/lustre/obdecho/echo_client.c:762:22-27: ERROR: ed
is NULL but dereferenced.

Signed-off-by: Cihangir Akturk <cakturk@gmail.com>
Acked-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>