ARM: shmobile: Use 64-bit dma_addr_t on r8a7790/r8a7791

Some on-chip devices on r8a7790 and r8a7791 can do
bus mastering and access more than 32-bits of address
space. Select ARCH_DMA_ADDR_T_64BIT when LPAE is set
in case of multiplatform and legacy SoC support.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>