sound: usb: qmi: Move QMI service init to driver probe

When registering the QMI server during initialization there is
a chance that the handle creation can fail with -EPROBE_DEFER if
the IPC router service isn't ready yet. In that case, we should
not fail the module_init call as that results in the module
getting unloaded with no automatic mechanism to reload it (a la
driver probe deferral). Instead, move the uaudio_qmi_svc_init()
call to beginning of uaudio_qmi_plat_probe() so that in case it
defers the probe can be retried again later.

Change-Id: I07a1e2cee5194387884cb716e95ed7c414a22159
Signed-off-by: Jack Pham <jackp@codeaurora.org>