PCI: rcar: Make the Kconfig dependencies more generic

Update the R-Car Generation 2 PCI driver Kconfig dependencies to follow
same style as other drivers - no SoC dependencies.

Also, update the COMPILE_TEST bits to depend on ARM. This since the DMA
bounce buffer and dma_ops handling code is ARM specific.

[bhelgaas: adjust context after dropping DMABOUNCE patches]
Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Simon Horman <horms+renesas@verge.net.au>