drivers/usb/host/ehci-msm.c: use devm_ functions

drivers/usb/host/ehci-msm.c: use devm_ functions

The various devm_ functions allocate memory that is released when a driver
detaches.  This patch uses these functions for data that is allocated in
the probe function of a platform device and is only freed in the remove
function.

The original code was also missing a call to iounmap(hcd->regs); in the
remove function, so this patch also implicitly fixes a bug.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>