staging: lustre: Fix "unsigned"->"unsigned int"

This patch fixes the checkpatch.pl warning:

WARNING:UNSPECIFIED_INT: Prefer 'unsigned int' to bare use of 'unsigned'

Signed-off-by: Sabin Mihai Rapan <sabin.rapan@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>