iommu/exynos: Remove unneeded local variable initialization

The initialization of 'fault_addr' local variable is not needed as it is
shortly after overwritten.

Addresses-Coverity: Unused value
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20210408201622.78009-1-krzysztof.kozlowski@canonical.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>