USB: EHCI: make ehci-msm a separate driver

Separate the  Qualcomm QSD/MSM on-chip host controller driver from
ehci-hcd host code so that it can be built as a separate driver module.
This work is part of enabling multi-platform kernels on ARM;
however, note that other changes are still needed before Qualcomm QSD/MSM
can be booted with a multi-platform kernel, which is not expected before
3.11.

With the infrastructure added by Alan Stern in patch 3e023203
"USB: EHCI: prepare to make ehci-hcd a library module", we can
avoid this problem by turning a bus glue into a separate
module, as we do here for the msm bus glue.

In V5 (arnd):
 - add FIXME about missing usb_add_hcd() or usb_remove_hcd() calls

In V3:
 - Detailed commit message added here describing why this patch is required.
 - Arranged  #include's in alphabetical order.
 - driver.name initialized hcd_name[] = "ehci-msm" in platform_driver
   structure initialization instead of "msm-ehci", which was the reason
   why it broke in EHCI USB testing

In V2:
Tegra patch related changes removed from this patch.

Signed-off-by: Manjunath Goudar <manjunath.goudar@linaro.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: David Brown <davidb@codeaurora.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>