dt-bindings: clock: r8a7779: Add PWM module clock

Add the module clock used by the PWM Timers on the Renesas R-Car H1
(R8A7779) SoC.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Link: https://lore.kernel.org/r/1397b[e-mail]

include/dt-bindings/clock/r8a7779-clock.h

···
 #define R8A7779_CLK_OUT		7
 
 /* MSTP 0 */
+#define R8A7779_CLK_PWM		5
 #define R8A7779_CLK_HSPI	7
 #define R8A7779_CLK_TMU2	14
 #define R8A7779_CLK_TMU1	15