swr: Use ElemenCount constructor for LLVM 11

In LLVM 12 ElementCount constructor is private
and instead of using it explicitly, ::get function
should be used, but in LLVM 11, the constructor
is still the way to go.

Reviewed-by: Krzysztof Raszkowski <krzysztof.raszkowski@intel.com>
Closes: #3490
Fixes: 639605e5ba947bb947313a6584ef7fbb8619e9c2
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6648>
2 files changed