serial: omap: fix compile breakage

when rebasing patches on top of Greg's tty-next,
it looks like automerge broke a few things which
I didn't catch (for whatever reason I didn't
have OMAP Serial enabled on .config) so I ended
up breaking the build on Greg's tty-next branch.

Fix the breakage by re-adding the three missing
members on struct uart_omap_port.

Reported-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>