iommu/iova: Add missing MODULE_DESCRIPTION() macro

With ARCH=arm, make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/iommu/iova.o

Add the missing invocation of the MODULE_DESCRIPTION() macro.

Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20240613-md-arm-drivers-iommu-v1-1-1fe0bd953119@quicinc.com


Signed-off-by: Joerg Roedel <jroedel@suse.de>