nir/lower_idiv: Port recent LLVM fixes to emit_udiv
This change fixes off-by-one results in corner cases such as 0xffffffff / 0x11111111. For details refer to LLVM bug 46212. Fixes: 8b98d095 ('nir/lower_idiv: add new llvm-based path') Reviewed-by:Rhys Perry <pendingchaos02@gmail.com> Part-of: <!6281> (cherry picked from commit 8277334f)