serial: pch_uart: fix build error with !CONFIG_DEBUG_FS

serial: pch_uart: fix build error with !CONFIG_DEBUG_FS

Fix the build error with CONFIG_DEBUG_FS is not set:

drivers/tty/serial/pch_uart.c: In function 'pch_uart_init_port':
drivers/tty/serial/pch_uart.c:1815:9: error: 'port_regs_ops' undeclared (first use in this function)
 1815 |        &port_regs_ops);
      |         ^~~~~~~~~~~~~

This commit get rid of the CONFIG_PM_SLEEP ifdefery to
fix the build error.

Fixes: 1f8a51ee3242 ("tty: serial: pch_uart.c: remove debugfs dentry pointer")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Link: https://lore.kernel.org/r/20210322122601.2980258-1-weiyongjun1@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>