usb: gadget: uvc: Fix ERR_PTR dereference in uvc_v4l2.c

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: uvc: Fix ERR_PTR dereference in uvc_v4l2.c Fix potential dereferencing of ERR_PTR() in find_format_by_pix() and uvc_v4l2_enum_format(). Fix the following smatch errors: drivers/usb/gadget/function/uvc_v4l2.c:124 find_format_by_pix() error: 'fmtdesc' dereferencing possible ERR_PTR() drivers/usb/gadget/function/uvc_v4l2.c:392 uvc_v4l2_enum_format() error: 'fmtdesc' dereferencing possible ERR_PTR() Also, fix similar issue in uvc_v4l2_try_format() for potential dereferencing of ERR_PTR().