common/nvdrv: improve memory validation and error handling

Implements several improvements to memory handling and validation:

- host_memory: Add IsValidMapping() and IsDirectMappingEnabled() methods to
  validate memory access
- host_memory: Fix virtual base offset calculation to use proper pointer
  arithmetic
- host_memory: Add size field to track allocation size
- nvhost_ctrl_gpu: Return InvalidState instead of InvalidValue for TPC mask
  buffer size validation
- Update copyright year for citron

The changes improve memory safety by adding explicit validation checks and
fixing pointer arithmetic in the virtual memory implementation.

src/core/hle/service/nvdrv/devices/nvhost_ctrl_gpu.cpp

@@ -270,7 +270,7 @@ NvResult nvhost_ctrl_gpu::GetTpcMasks2(IoctlGetTpcMasks& params) {
     // Validate input parameters
     if (params.mask_buf_size == 0 || params.mask_buf_size > params.tpc_mask_buf.size()) {
         LOG_ERROR(Service_NVDRV, "Invalid mask buffer size {}", params.mask_buf_size);
-        return NvResult::InvalidValue;
+        return NvResult::InvalidState;
     }
 
     // Set up TPC mask values based on GPU configuration