usb: gadget: f_uac2: Add HS/SS bInterval to configfs

Allow configuring the HS/SS bInterval through configfs, via
parameters p_hs_bint/c_hs_bint separately for playback/capture.

The default param values are left at the original 4.

Suggested-by: John Keeping <john@metanate.com>
Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com>
Link: https://lore.kernel.org/r/20220127114331.41367-2-pavel.hofman@ivitera.com


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