arch/alpha/kernel: Add kmalloc NULL tests

Check that the result of kmalloc is not NULL before passing it to other
functions.

The semantic match that finds this problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
expression *x;
identifier f;
constant char *C;
@@

x = \(kmalloc\|kcalloc\|kzalloc\)(...);
... when != x == NULL
when != x != NULL
when != (x || ...)
(
kfree(x)
f(...,C,...,x,...)
|
*f(...,x,...)
|
*x->f
)
// </smpl>

Signed-off-by: Julia Lawall <[e-mail]>
Cc: Ivan Kokshaysky <[e-mail]>
Cc: Richard Henderson <[e-mail]>
Signed-off-by: Matt Turner <[e-mail]>

arch/alpha/kernel/core_marvel.c

···
 	 * Allocate the info structure.
 	 */
 	agp = kmalloc(sizeof(*agp), GFP_KERNEL);
+	if (!agp)
+		return NULL;
 
 	/*
 	 * Fill it in.

arch/alpha/kernel/core_titan.c

···
 	 * Allocate the info structure.
 	 */
 	agp = kmalloc(sizeof(*agp), GFP_KERNEL);
+	if (!agp)
+		return NULL;
 
 	/*
 	 * Fill it in.