media: Staging: media: atomisp: Use kcalloc instead of kzalloc

Use kcalloc instead of kzalloc to check for an overflow before
multiplication. Done using the following semantic patch by
coccinelle.

http://coccinelle.lip6.fr/rules/kzalloc.cocci

Signed-off-by: Srishti Sharma <srishtishar@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>