Staging: lustre: lproc_ptlrpc: Replace simple_strtol with simple_stroul

The variable inst is a __u32 type and hence the function used should be
simple_strtoul.
Semantic patch used:

@@
typedef __u32;
__u32 e;
@@
e =
- simple_strtol
+ simple_strtoul
  (...)

Signed-off-by: Shivani Bhardwaj <shivanib134@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>