staging: fbtft: Use kmalloc_array

Use kmalloc_array instead of kmalloc for arrays to prevent integer
overflows.
This was done using Coccinelle:

@@
expression e1, e2;
constant C;
type t;
@@
(
- kmalloc(
+ kmalloc_array(
e2
- *
+ ,
sizeof(e1), C)
|
- kmalloc(
+ kmalloc_array(
e1
- *
+ ,
sizeof(t), C)
|
- kmalloc(
+ kmalloc_array(
- sizeof(e1)
- *
e2
+ ,
+ sizeof(e1)
, C)
|
- kmalloc(
+ kmalloc_array(
- sizeof(t)
- *
e1
+ ,
+ sizeof(t)
, C)
)

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>