iommu/ipmmu-vmsa: Increase maximum micro-TLBS to 48

Bump up the maximum numbers of micro-TLBS to 48.

Each IPMMU device instance get micro-TLB assignment via
the "iommus" property in DT. Older SoCs tend to use a
maximum number of 32 micro-TLBs per IPMMU instance however
newer SoCs such as r8a7796 make use of up to 48 micro-TLBs.

At this point no SoC specific handling is done to validate
the maximum number of micro-TLBs, and because of that the
DT information is assumed to be within correct range for
each particular SoC.

If needed in the future SoC specific feature flags can be
added to handle the maximum number of micro-TLBs without
requiring DT changes, however at this point this does not
seem necessary.

Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
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>