ALSA: usb-audio: qcom: fix USB_XHCI dependency

ALSA: usb-audio: qcom: fix USB_XHCI dependency

SND_USB_AUDIO_QMI depends on USB_XHCI_SIDEBAND, but that is a bool symbol
and allows it to be built-in even when XHCI itself is in a loadable module.
That configuration causes a link failure:

arm-linux-gnueabi-ld: sound/usb/qcom/qc_audio_offload.o: in function `uaudio_event_ring_cleanup_free':
qc_audio_offload.c:(.text+0x7dc): undefined reference to `xhci_sideband_remove_interrupter'
arm-linux-gnueabi-ld: sound/usb/qcom/qc_audio_offload.o: in function `uaudio_endpoint_setup':
qc_audio_offload.c:(.text+0xe88): undefined reference to `xhci_sideband_add_endpoint'

Add the extra dependency on USB_XHCI itself.

Fixes: 326bbc348298 ("ALSA: usb-audio: qcom: Introduce QC USB SND offloading support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20250521135551.2111109-1-arnd@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>