Move "uart_console" definition to serial core header file, so that it can be
used by serial drivers.
Get rid of the uart_console defintion from mpc52xx_uart driver.

Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Rajendra nayak <rnayak@ti.com>
Reviewed-by: NFelipe Balbi <balbi@ti.com>
Reviewed-by: NKevin Hilman <khilman@linaro.org>
Tested-by: NKevin Hilman <khilman@linaro.org>
Signed-off-by: NSourav Poddar <sourav.poddar@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>