dt-bindings: clock: ast2600: Add top-level I3C clock

The ast2600 hardware has a top-level clock for all i3c controller
peripherals (then gated to each individual controller), so add a
top-level i3c clock line to control this.

This is a partial cherry-pick and rework of ed44b8c and 1a35eb9
from Aspeed's own tree, originally by Dylan Hung
<[email protected]>.

Acked-by: Krzysztof Kozlowski <[email protected]>
Reviewed-by: Joel Stanley <[email protected]>
Signed-off-by: Jeremy Kerr <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Tested-by: Joel Stanley <[email protected]>
Signed-off-by: Stephen Boyd <[email protected]>

Author: jk-ozlabs

include/dt-bindings/clock/ast2600-clock.h

@@ -87,6 +87,7 @@
 #define ASPEED_CLK_MAC2RCLK		68
 #define ASPEED_CLK_MAC3RCLK		69
 #define ASPEED_CLK_MAC4RCLK		70
+#define ASPEED_CLK_I3C			71
 
 /* Only list resets here that are not part of a gate */
 #define ASPEED_RESET_ADC		55