staging: dgap: Use unsigned for loop index

The following semantic patch is used to do this

@r exists@ // find anything that might decrement the variable
identifier i;
expression E;
position p;
@@

  int i@p;
  ...
(
  &i
|
  i--
|
  --i
|
  i-=E
|
  i+=E
)

@x disable decl_init@
identifier r.i;
expression E;
position p1 != r.p;
@@

(
  volatile int i = 0;
|
  volatile int i;
|
+ unsigned
  int i@p1 = 0;
|
+ unsigned
  int i@p1;
)
  <... when != i = E
(
  i = 0
|
  i = 1
)
  ...>

Signed-off-by: Tapasweni Pathak <tapaswenipathak@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>