Fix harmless if statements with empty body, spotted by clang

Fix harmless if statements with empty body, spotted by clang

These clang errors are harmless but worth fixing:
  CC    libhw64/fdc.o
/src/qemu/hw/fdc.c:998:74: error: if statement has empty body [-Wempty-body]
        FLOPPY_DPRINTF("Floppy digital input register: 0x%02x\n", retval);
  CC    libhw64/cuda.o
/src/qemu/hw/cuda.c:320:66: error: if statement has empty body [-Wempty-body]
        CUDA_DPRINTF("read: reg=0x%x val=%02x\n", (int)addr, val);

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>