tty: serial: bcm63xx: fix missing clk_put() in bcm63xx_uart

tty: serial: bcm63xx: fix missing clk_put() in bcm63xx_uart

This patch fixes below error reported by coccicheck

drivers/tty/serial/bcm63xx_uart.c:848:2-8: ERROR: missing clk_put;
clk_get on line 842 and execution via conditional on line 846

Fixes: 526fb0dc55b8 ("tty: move drivers/serial/ to drivers/tty/serial/")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/1587472306-105155-1-git-send-email-zou_wei@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>