amba: tegra-ahb: enable compile testing

amba: tegra-ahb: enable compile testing

There seems to be nothing preventing this driver from being compile
tested so enable that to increase build coverage.

This also allows for compile testing of further Tegra drivers (e.g.
IOMMU driver).

Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>