LoongArch: Remove the unused dma-direct.h

commit 58aec91efb93338d1cc7acc0a93242613a2a4e5f upstream.

dma-direct.h is introduced in commit d4b6f15 ("LoongArch: Add
Non-Uniform Memory Access (NUMA) support"). In commit c78c43f
("LoongArch: Use acpi_arch_dma_setup() and remove ARCH_HAS_PHYS_TO_DMA"),
ARCH_HAS_PHYS_TO_DMA was deselected and the coresponding phys_to_dma()/
dma_to_phys() functions were removed. However, the unused dma-direct.h
was left behind, which is removed by this patch.

Cc: <[email protected]>
Fixes: c78c43f ("LoongArch: Use acpi_arch_dma_setup() and remove ARCH_HAS_PHYS_TO_DMA")
Signed-off-by: Miao Wang <[email protected]>
Signed-off-by: Huacai Chen <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>