ARM: s3c24xx: Simplify size used for kzalloc in iotiming get

Simplify the size argument of kzalloc() memory allocation by using
sizeof(*ptr) syntax.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
[krzk: Rewrite commit message]
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>