[Decode][PDVT-SH] Refactor HEVC decode pipeline inheritance hierarchy

* [Decode] Refactor HEVC decode pipeline inheritance hierarchy
Refactored HEVC decode pipeline adapter and pipeline classes to use inheritance from previous generation base classes. Moved common functionality to base classes, reducing code duplication by ~540 lines. The adapter now inherits from previous generation adapter and only overrides Allocate() to instantiate platform-specific pipeline. Pipeline class similarly inherits from previous generation and only overrides CreateSubPackets(). Command counter register handling moved from base MMIO structure to extension structure for better modularity. This change improves code maintainability and reduces duplication across platform variants.

Author: pengwan1

media_softlet/agnostic/common/hw/vdbox/mhw_vdbox_hcp_cmdpar.h

@@ -113,8 +113,6 @@ struct HcpMmioRegisters
     uint32_t hcpDecStatusRegOffset;
     uint32_t hcpCabacStatusRegOffset;
     uint32_t hcpFrameCrcRegOffset;
-    uint32_t hcpCommandCounterRegOffset;
-    uint32_t hcpCommandCounterOverrideRegOffset;
 };
 
 struct HcpBufferSizePar

media_softlet/agnostic/common/hw/vdbox/mhw_vdbox_hcp_impl.h

@@ -764,8 +764,6 @@ class Impl : public Itf, public mhw::Impl
         mmioRegisters->hcpDecStatusRegOffset                             = HCP_DEC_STATUS_REG_OFFSET_INIT;
         mmioRegisters->hcpCabacStatusRegOffset                           = HCP_CABAC_STATUS_REG_OFFSET_INIT;
         mmioRegisters->hcpFrameCrcRegOffset                              = HCP_FRAME_CRC_REG_OFFSET_INIT;
-        mmioRegisters->hcpCommandCounterRegOffset                        = HCP_COMMAND_COUNTER_REG_OFFSET_INIT;
-        mmioRegisters->hcpCommandCounterOverrideRegOffset                = HCP_COMMAND_COUNTER_OVERRIDE_REG_OFFSET_INIT;
 
         m_mmioRegisters[MHW_VDBOX_NODE_2] = m_mmioRegisters[MHW_VDBOX_NODE_1];
     }