watchdog: imx2_wdt.c: use devm_request_and_ioremap

Reimplement a call to devm_request_mem_region followed by a call to ioremap
or ioremap_nocache by a call to devm_request_and_ioremap.

The variable res_size is then no longer needed.

The semantic patch that makes this transformation is as follows:
(http://coccinelle.lip6.fr/

)

// <smpl>
@nm@
expression myname;
identifier i;
@@

struct platform_driver i = { .driver = { .name = myname } };

@@
expression dev,res,size;
expression nm.myname;
@@

-if (!devm_request_mem_region(dev, res->start, size,
-                              \(res->name\|dev_name(dev)\|myname\))) {
-   ...
-   return ...;
-}
... when != res->start
(
-devm_ioremap(dev,res->start,size)
+devm_request_and_ioremap(dev,res)
|
-devm_ioremap_nocache(dev,res->start,size)
+devm_request_and_ioremap(dev,res)
)
... when any
    when != res->start
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>