hw/riscv/riscv-iommu-sys.c: fix duplicated 'table_size'

Trivial fix for the following ticket:

CID 1568580:  Incorrect expression  (EVALUATION_ORDER)
In "table_size = table_size = n_vectors * 16U",
    "table_size" is written twice with the same value.

Cc: qemu-trivial@nongnu.org
Cc: Peter Maydell <peter.maydell@linaro.org>
Resolves: Coverity CID 1568580
Fixes: 01c1caa9d1 ("hw/riscv/virt.c, riscv-iommu-sys.c: add MSIx support")
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

hw/riscv/riscv-iommu-sys.c

@@ -121,7 +121,7 @@ static void riscv_iommu_sysdev_init_msi(RISCVIOMMUStateSys *s,
                                         uint32_t n_vectors)
 {
     RISCVIOMMUState *iommu = &s->iommu;
-    uint32_t table_size = table_size = n_vectors * PCI_MSIX_ENTRY_SIZE;
+    uint32_t table_size = n_vectors * PCI_MSIX_ENTRY_SIZE;
     uint32_t table_offset = RISCV_IOMMU_REG_MSI_CONFIG;
     uint32_t pba_size = QEMU_ALIGN_UP(n_vectors, 64) / 8;
     uint32_t pba_offset = RISCV_IOMMU_REG_MSI_CONFIG + 256;