USB: MAINTAINERS update, EHCI and OHCI

Update maintainer records for two USB host controller drivers.  I'm the
main point of contact for both EHCI and OHCI, although I don't have much
time for them any more.  Roman hasn't submitted OHCI patches for years.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>