tty: serial: msm: Move header file into driver

This header file is only used by the driver, so let's merge the
two together to reduce files and make it easier to see the whole
driver without flipping through two files. This also makes it
easier to use the structures defined in msm_serial.c in the
functions that are defined in msm_serial.h by placing them in the
proper locations.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Andy Gross <andy.gross@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>