tty: serial: 8250: Fix multi-line strings

Merged user-visible multi-line strings into a single line according to the
Linux Kernel Coding Style, which allows user-visible strings to exceed the
maximum line length of 80 characters. The main reason for this is to
facilitate grepping for these strings.
However, some strings were ignored in this patch, because the use of
format specifiers breaks the ability to grep anyway.

Signed-off-by: Anton Würfel <anton.wuerfel@fau.de>
Signed-off-by: Phillip Raffeck <phillip.raffeck@fau.de>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: linux-kernel@i4.cs.fau.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>