linux-libc-headers: bump to 6.1

6.1 is a LTS and one of the reference kernels for our next
relase. Making it a logical update point for our libc-headers.

We can drop one of our patche as the gcc-goto.sh is no longer
used, and hence we won't have race conditions like we previously
had.

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>