serial: 8250_em: Use devm_clk_get_enabled()

Simplify clk handling in probe() by replacing devm_clk_get()->devm_
clk_get_enabled(). This replaces the usage of clk_prepare_enable/clk_
disable_unprepare() in probe()/remove(). After that sclk is no
longer required in struct serial8250_em_priv and is replaced by a
local variable sclk in probe().

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20230227114152.22265-6-biju.das.jz@bp.renesas.com


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