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

drivers/tty/serial/pch_uart.c

@@ -291,8 +291,6 @@ static const int trigger_level_64[4] = { 1, 16, 32, 56 };
 static const int trigger_level_16[4] = { 1, 4, 8, 14 };
 static const int trigger_level_1[4] = { 1, 1, 1, 1 };
 
-#ifdef CONFIG_DEBUG_FS
-
 #define PCH_REGS_BUFSIZE	1024
 
 
@@ -352,7 +350,6 @@ static const struct file_operations port_regs_ops = {
 	.read		= port_show_regs,
 	.llseek		= default_llseek,
 };
-#endif	/* CONFIG_DEBUG_FS */
 
 static const struct dmi_system_id pch_uart_dmi_table[] = {
 	{