gpu: host1x: Fix iommu_map_sgtable() return value check

In the Linux kernel, the following vulnerability has been resolved: gpu: host1x: Fix iommu_map_sgtable() return value check Commit "iommu: return full error code from iommu_map_sg[_atomic]()" changed iommu_map_sgtable() to return an ssize_t and negative values in error cases, rather than a size_t and a zero. pin_job() also was incorrectly assigning to 'int', which could cause overflows into negative values. Update pin_job() to correctly check for errors from iommu_map_sgtable.