drivers:tty: fix return value check in asc_init_port

in asc_init_port, clk_prepare_enable may fail, therefore, the
return value of clk_prepare_enable should be checked.

Signed-off-by: Yuanjun Gong <ruc_gongyuanjun@163.com>
Link: https://lore.kernel.org/r/20230717144733.24194-1-ruc_gongyuanjun@163.com


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