Staging: lustre: lustre: mdc: mdc_request: Removed useless variable

Variable rc is initialised and returned by the function without modifying.
Hence replaced rc with it's initial value in the return statement and
removed the variable.

Signed-off-by: Tina Johnson <tinajohnson.1234@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>