lib: raid6: fix awk build warnings

Newer versions of awk spit out these fun warnings:
awk: ../lib/raid6/unroll.awk:16: warning: regexp escape sequence `\#' is not a known regexp operator

As commit 700c1018b86d ("x86/insn: Fix awk regexp warnings") showed, it
turns out that there are a number of awk strings that do not need to be
escaped and newer versions of awk now warn about this.

Fix the string up so that no warning is produced. The exact same kernel
module gets created before and after this patch, showing that it wasn't
needed.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20191206152600.GA75093@kroah.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>