tty: serial: samsung: add spin_lock for interrupt and console_write

The console_write and IRQ handler can run concurrently.
Problems may occurs console_write is continuously executed while
the IRQ handler is running.

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com>
Link: https://lore.kernel.org/r/20220407071619.102249-2-jaewon02.kim@samsung.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>