hw/riscv/riscv-iommu-bits: Remove duplicate definitions

hw/riscv/riscv-iommu-bits: Remove duplicate definitions

The header contains duplicate macro definitions.
This commit eliminates the duplicate part.

Signed-off-by: Jason Chien <jason.chien@sifive.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20250115141730.30858-2-jason.chien@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>