intel/compiler: Don't create 64-bit src1 immediates in opt_peephole_sel

intel/compiler: Don't create 64-bit src1 immediates in opt_peephole_sel

64-bit immediates are only allowed as src0.  Long ago, we decided to
avoid constructing such illegal situations in the IR, rather than
allowing them in the IR but then promoting bogus immediates to GRFs
later.  So, we need to fix opt_peephole_sel to not put 64-bit immediates
as src1 of the new SEL instruction.

Fixes: a4b36cd3dd3 ("intel/fs: Coalesce when the src live range is contained in the dst")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/2816
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4692>