clk: renesas: rzg2l: Add missing kerneldoc for resets

make W=1:

    drivers/clk/renesas/rzg2l-cpg.c:95: warning: Function parameter or member 'num_resets' not described in 'rzg2l_cpg_priv'

Add the missing kerneldoc for fields in struct rzg2l_cpg_priv and struct
rzg2l_cpg_info related to Module Resets.

Fixes: c3e67ad6 ("dt-bindings: clock: r9a07g044-cpg: Update clock/reset definitions")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/39c2c5fd4232b6620a4a56dba4e2b0d61476ee36.1634646869.git.geert+renesas@glider.be