arm-bsp-extras/dts: Fix warnings for arm,mhuv3 nodes in rdkronos.dts

For all nodes for arm,mhuv3:
- Change interrupt-names = "combined"; "combined-pbx" is not allowed
  per schema file.
- Remove clock-names, it is not defined (additionalProperties=false).
- Change interrupts to use macros in Linux header file and have a
  consistent style with other nodes.

Notes: There are dt-validate warnings for clock-names like:
mhu@2aea0000: 'clock-names' does not match any of the regexes:
'pinctrl-[0-9]+' from schema
$id: http://devicetree.org/schemas/mailbox/arm,mhuv3.yaml#



Signed-off-by: Jun Wu <jun.wu@arm.com>