usb/host/fotg210: Add function scan_frame_queue()

checkpatch complains about too many leading tabs because the if
statement starts after 6 tabs:

scan_iosoc() -> for() -> while() -> switch() -> if() -> for() -> if()

There is also a goto statement going backwards in case of failure. This
patch creates a new inline function named scan_frame_queue() containing
the last 4 nesting levels, and removes the need of backwards goto,
making the code easier to read. After the patch it becomes:

scan_iosoc() -> for() -> while() -> scan_frame_queue()

Signed-off-by: Peter Senna Tschudin <peter.senna@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>