Match parameter order between float and integer sampling.

Change-Id: I86333f0f4d8a9e180a2f7f902d865b664eb836eb
Reviewed-on: https://swiftshader-review.googlesource.com/3102
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>