serial: core: Fix ifdef for serial base console functions

serial: core: Fix ifdef for serial base console functions

If CONFIG_SERIAL_CORE_CONSOLE is not set, we get build errors.
Let's fix the issue by moving the endif after the serial base console
functions.

Fixes: 4547cd76f08a ("serial: 8250: Fix add preferred console for serial8250_isa_init_ports()")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202404131416.VJljwvkS-lkp@intel.com/
Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20240413103343.24231-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>