serial: treewide: Remove empty implementations of enable_ms()

drivers/tty/serial/21285.c

drivers/tty/serial/altera_jtaguart.c

drivers/tty/serial/altera_uart.c

drivers/tty/serial/apbuart.c

drivers/tty/serial/ar933x_uart.c

drivers/tty/serial/arc_uart.c

drivers/tty/serial/bfin_sport_uart.c

drivers/tty/serial/bfin_uart.c

drivers/tty/serial/clps711x.c

drivers/tty/serial/cpm_uart/cpm_uart_core.c

drivers/tty/serial/dz.c

drivers/tty/serial/efm32-uart.c

drivers/tty/serial/fsl_lpuart.c

drivers/tty/serial/icom.c

drivers/tty/serial/ioc3_serial.c

drivers/tty/serial/ioc4_serial.c

drivers/tty/serial/jsm/jsm_tty.c

drivers/tty/serial/lantiq.c

drivers/tty/serial/lpc32xx_hs.c

drivers/tty/serial/max310x.c