usb: ehci-platform: add reset controller number in struct ehci_platform_priv

Some ehci compatible controllers have more than one reset signal lines,
e.g., Synopsys DWC USB2.0 Host-AHB Controller has two resets hreset_i_n
and phy_rst_i_n. Two more resets are added in this patch in order for
this kind of controller to use this driver directly.

Signed-off-by: Jiancheng Xue <xuejiancheng@hisilicon.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>