staging:dwc2:hcd_queue.c : cleanups to the microframe scheduler code

This patch takes up the task mentioned in the TODO file of dwc2 to
cleanup the microframe scheduler code. The while(!done) loops have been
replaced with appropriate for loops and unnecessary variables
like done and ret have been removed.

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>