usb:gadget: f_uac1: fixed sync playback

usb:gadget: f_uac1: fixed sync playback

The u_audio param fb_max was not set to its default value in f_uac1.c.
As a result the maximum value of Playback Pitch ctl was kept at 1000000,
not allowing to set faster playback pitch for UAC1.

The setting required moving the default constant UAC2_DEF_FB_MAX from
u_uac2.h to FBACK_FAST_MAX in u_audio.h as that header is common for
f_uac1.c and f_uac2.c.

Fixes: 6fec018a7e70 ("usb: gadget: u_audio.c: Adding Playback Pitch ctl for sync playback")
Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com>
Link: https://lore.kernel.org/r/20211022140339.248669-1-pavel.hofman@ivitera.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>