EHCI: msm: Use ehci_setup to clean up duplicate code

Most of the ehci_reset code is moved to ehci_setup. Hence, start
using this API instead of duplicating code in platform specific
ehci_reset routines.

Change-Id: Ifc7874c72f75f963825586678e0a070afd65d1bd
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>