Input: imx6ul_tsc - use the preferred method for kzalloc()

According to Documentation/CodingStyle:

"The preferred form for passing a size of a struct is the following:

	p = kmalloc(sizeof(*p), ...);"

so do as suggested.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>