ACPI/IORT: Remove obsolete ACPI_IORT_SMMU_V3_CAVIUM_CN99XX define

To defeat ACPICA<->kernel merge order dependencies a preprocessor define
value was introduced in the IORT compilation unit according to IORT
revision C, IORT_SMMU_V3_CAVIUM_CN99XX, so that even if the value was
not defined in ACPICA headers the IORT kernel layer would still be able
to function and use it.

Since commit 0c2021c0

 ("ACPICA: IORT: Update SMMU models for
revision C") finally added the define in ACPICA headers, as required by
ACPICA IORT support, the preprocessor definition in the IORT kernel
compilation unit has become obsolete and can be removed.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>