USB: r8a66597-hcd: fixes some problem

This patch incorporates some updates. Updates include:

 - Fix the problem that control transfer might fail
 - Change from GFP_KERNEL to GFP_ATOMIC
 - Clean up some coding style issue

Signed-off-by: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>