iommu/ipmmu-vmsa: Add an array of slave devices whitelist

To avoid adding copy and pasted strcmp codes in the future,
this patch adds an array "rcar_gen3_slave_whitelist" to check
whether the device can work with the IPMMU or not.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Joerg Roedel <jroedel@suse.de>