x86: ivybridge: Drop special EHCI init

This is not needed. On reset wake-on-disconnect is already set. It may a
problem during a soft reset or resume, but for now it does not seem
important. Also drop the command register update since PCI auto-config
does it for us.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>