arch: hexagon: Kconfig: add HAVE_DMA_ATTR in Kconfig and remove "linux/dma-mapping.h" from "asm/dma-mapping.h"

When HAS_DMA, and also need use generic implementation, HAVE_DMA_ATTR
must be enabled, or can not pass compiling with allmodconfig, the
related error:

    CC [M]  drivers/ata/libata-core.o
  drivers/ata/libata-core.c: In function 'ata_sg_clean':
  drivers/ata/libata-core.c:4598:3: error: implicit declaration of function 'dma_unmap_sg' [-Werror=implicit-function-declaration]
  drivers/ata/libata-core.c: In function 'ata_sg_setup':
  drivers/ata/libata-core.c:4708:2: error: implicit declaration of function 'dma_map_sg' [-Werror=implicit-function-declaration]

"linux/dma-mapping.h" will include "asm/dma-mapping.h", so need remove
"linux/dma-mapping.h" from "asm/dma-mapping.h",
Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: Richard Kuo <rkuo@codeaurora.org>