usb: chipidea: ci_hdrc_imx: fix usbmisc handling

usbmisc is an optional device property so it is totally valid for the
corresponding data->usbmisc_data to have a NULL value.

Check that before dereferencing the pointer.

Found by Linux Verification Center (linuxtesting.org) with Svace static
analysis tool.

Fixes: 74adad50 ("usb: chipidea: ci_hdrc_imx: decrement device's refcount in .remove() and in the error path of .probe()")
Cc: stable <stable@kernel.org>
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Acked-by: Peter Chen <peter.chen@kernel.org>
Link: https://lore.kernel.org/r/20250316102658.490340-2-pchelkin@ispras.ru


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>