mfd: omap-usb-tll: Allocate driver data at once

Allocating memory to store clk array together with driver
data simplifies error unwinding and allows deleting memory
allocation failure message as there is now only single point
of failure already covered by allocation failure report.

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
[Markus Elfring: simplified error unwinding, error message removal]
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Acked-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>