usb: musb: dsps: fix error return code in dsps_create_musb_pdev()

Fix to return -ENOMEM in the devm_kzalloc() error handling
case instead of 0, as done elsewhere in this function.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Felipe Balbi <balbi@ti.com>