FROMLIST: usb: gadget: f_uac2: fixed EP-IN wMaxPacketSize

Async feedback patches broke enumeration on Windows 10 previously fixed
by commit 789ea773 ("usb: gadget: f_uac2: always increase endpoint
max_packet_size by one audio slot").

While the existing calculation for EP OUT capture for async mode yields
size+1 frame due to uac2_opts->fb_max > 0, playback side lost the +1
feature.  Therefore the +1 frame addition must be re-introduced for
playback. Win10 enumerates the device only when both EP IN and EP OUT
max packet sizes are (at least) +1 frame.

Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com>
Tested-by: Henrik Enquist <henrik.enquist@gmail.com>
Tested-by: Jack Pham <jackp@codeaurora.org>
Bug: 199044440
Link: https://lore.kernel.org/linux-usb/b11414f0-1783-192e-2b79-066dd4c814d0@ivitera.com/


Change-Id: I74994d717b0eb543104e3ed7b20ca06c7c584be9
Signed-off-by: Jack Pham <jackp@codeaurora.org>