drm/gem: rename struct drm_gem_dma_object.{paddr => dma_addr}

drm/gem: rename struct drm_gem_dma_object.{paddr => dma_addr}

The field paddr of struct drm_gem_dma_object holds a DMA address, which
might actually be a physical address. However, depending on the platform,
it can also be a bus address or a virtual address managed by an IOMMU.

Hence, rename the field to dma_addr, which is more applicable.

In order to do this renaming the following coccinelle script was used:

```
	@@
	struct drm_gem_dma_object *gem;
	@@

	- gem->paddr
	+ gem->dma_addr

	@@
	struct drm_gem_dma_object gem;
	@@

	- gem.paddr
	+ gem.dma_addr

	@exists@
	typedef dma_addr_t;
	symbol paddr;
	@@

	dma_addr_t paddr;
	<...
	- paddr
	+ dma_addr
	...>

	@@
	symbol paddr;
	@@
	dma_addr_t
	- paddr
	+ dma_addr
	;

```

This patch is compile-time tested with:

```
	make ARCH={x86_64,arm,arm64} allyesconfig
	make ARCH={x86_64,arm,arm64} drivers/gpu/drm`
```

Acked-by: Sam Ravnborg <sam@ravnborg.org>
Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220802000405.949236-5-dakr@redhat.com