Fix clock index out of range check for module clocks in
rzg2l_cpg_clk_src_twocell_get().

Fixes: ef3c613c ("clk: renesas: Add CPG core wrapper for RZ/G2L SoC")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20210617155432.18827-1-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>