clk: renesas: rzg2l: Simplify the logic in rzg2l_mod_clock_endisable()

The bitmask << 16 is anyway set on both branches of if thus move it
before the if and set the lower bits of registers only in case clock is
enabled.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230912045157.177966-12-claudiu.beznea.uj@bp.renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>