serial: clps711x: drop needless devm_clk_put

The nice thing about devm_* is that the driver doesn't need to free the
resources but the driver core takes care about that.

These calls were introduced in commit c08f0153 (serial: clps711x: Using
CPU clock subsystem for getting base UART speed).

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Alexander Shiyan <shc_work@mail.ru>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>