[U-Boot] S3C2440 "usb start" and then "usb stop" cause nand operate failure.

[wesley xie]

Hi, guys here.

for u-boot-2010.03(also u-boot-2010.05 I belive) on s3c2440,

if I "usb start" and then "usb stop", all of the nand operate will report
failure.

I look into the u-boot code, and found that it seems something wrong in
s3c24x0 usb code, see below.