serial: samsung: fix omission initialize ulcon in reset port fn()

Fix omission initialize ulcon in s3c24xx_serial_resetport(),
reset port function in drivers/tty/serial/samsung.c. It has
been happened from commit 0dfb3b41("serial: samsung: merge
all SoC specific port reset functions")

Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Cc: stable <stable@vger.kernel.org> [3.3]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>