dt-bindings: power: qcom,rpmhpd: Add RPMh power domain for Hawi SoC

dt-bindings: power: qcom,rpmhpd: Add RPMh power domain for Hawi SoC

Document the RPMh power domain for Hawi SoC, and add definitions for
the new power domains which present in Hawi SoC:
 - RPMHPD_DCX (Display Core X): supplies VDD_DISP for the display
   subsystem
 - RPMHPD_GBX (Graphics Box): supplies VDD_GFX_BX for the GPU/graphics
   subsystem

Also, add constants for new power domain levels that supported in Hawi
SoC, including: LOW_SVS_D3_0, LOW_SVS_D1_0, LOW_SVS_D0_0, SVS_L2_0,
TURBO_L1_0/1/2, TURBO_L1_0/1/2.

Signed-off-by: Fenglin Wu <fenglin.wu@oss.qualcomm.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>