fotg210: Use ehci_dbg_port struct

The FOTG210 debug port has a EHCI-compatible register layout so there is
no need to define a custom struct.

Signed-off-by: Chris Rorvick <chris@rorvick.com>
usb: Remove __init from early_dbgp_init() prototype

Specifying these attributes in both the prototype and the function
definition is unnecessary and could cause confusion or bugs if they are
inconsistent.  As such, __init should only be specified at the function
definition.

Keith Owens suggested this as a janitorial task on LKML several years
ago:

  https://lkml.org/lkml/2006/1/14/305

Signed-off-by: Chris Rorvick <chris@rorvick.com>