dt-bindings: clock: r9a07g043-cpg: Annotate RZ/G2UL-only core clocks

The M2 (CRU main clock), M3 (LCDC Video Clock), and AT (Cortex-A55 Debug
clock) core clocks are only present on RZ/G2UL, not on RZ/Five.

Annotate this in the comments, like is already done for module clocks
and resets.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/ffcdcd479c76b92f67481836a33ec86e97f85634.1708944903.git.geert+renesas@glider.be

include/dt-bindings/clock/r9a07g043-cpg.h

@@ -16,15 +16,15 @@
 #define R9A07G043_CLK_SD0		5
 #define R9A07G043_CLK_SD1		6
 #define R9A07G043_CLK_M0		7
-#define R9A07G043_CLK_M2		8
-#define R9A07G043_CLK_M3		9
+#define R9A07G043_CLK_M2		8	/* RZ/G2UL Only */
+#define R9A07G043_CLK_M3		9	/* RZ/G2UL Only */
 #define R9A07G043_CLK_HP		10
 #define R9A07G043_CLK_TSU		11
 #define R9A07G043_CLK_ZT		12
 #define R9A07G043_CLK_P0		13
 #define R9A07G043_CLK_P1		14
 #define R9A07G043_CLK_P2		15
-#define R9A07G043_CLK_AT		16
+#define R9A07G043_CLK_AT		16	/* RZ/G2UL Only */
 #define R9A07G043_OSCCLK		17
 #define R9A07G043_CLK_P0_DIV2		18