OMAP: Serial: Define OMAP uart MDR1 reg and remove magic numbers

Define MDR1 register serial definitions used in serial and
bluetooth drivers.
Change magic number to ones defined in serial_reg for omap1/2
serial driver.
Remove redefined MDR1 register definitions in omap-serial driver.

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@nokia.com>
Acked-by: G, Manjunath Kondaiah <manjugk@ti.com>
Acked-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Tony Lindgren <tony@atomide.com>