printing hex value prints random values

[jcasas00]

    def kernel():
        stype = hcl.Struct({"x": hcl.UInt(8), "y": hcl.UInt(8)})
        xy = hcl.scalar(0x1234, "foo", dtype=stype).v
        hcl.print((xy.x, xy.y), "dec: %d %d\n")
        hcl.print((xy.x, xy.y), "hex: %x %x\n")

generates:

match 0: 52 18
match 0: 0 598f4740

The "hex" print actually prints random values (number changes every run).

[zzzDavid]

%x format string hasn't been supported in the LLVM backend, let me add that

[zzzDavid]

llvm.mlir.printf only support f64 input type. Currently we are casting integers to float first and use .0f as a replacement for %d. We should implement our own print utility function that supports %x and %X format string