linuxPackages_testing.perf: fix patchShebang

Without the change `perf` build fails as:

    $ nix build --no-link -f. linuxPackages_testing.perf -L

    build flags: SHELL=/nix/store/p6dlr3skfhxpyphipg2bqnj52999banh-bash-5.2-p15/bin/bash prefix=\$\(out\) WERROR=0 ASCIIDOC8=1 O=\$\(buildRoot\) CC=/nix/store/bxic6j2whyg3z4h2x3xjyqgp7fl83bnp-gcc-wrapper-12.3.0/bin/cc HOSTCC=/nix/store/bxic6j2whyg3z4h2x3xjyqgp7fl83bnp-gcc-wrapper-12.3.0/bin/cc HOSTLD=/nix/store/kcp78dk7h5gcs7d4qss7rbz3skxhzdnn-binutils-wrapper-2.40/bin/ld ARCH=x86_64 NO_GTK2=1
      BUILD:   Doing 'make -j16' parallel build
      HOSTCC  fixdep.o
      HOSTLD  fixdep-in.o
      LINK    fixdep
    make[1]: ./check-headers.sh: No such file or directory
    make[1]: *** [Makefile.perf:241: sub-make] Error 127
    make: *** [Makefile:70: all] Error 2

This started happening because upstream linux commit
    https://github.com/torvalds/linux/commit/d6748385098a8333a0e1c7e2d77119c919776728
changed shebang from /bin/sh to /bin/bash.

Let's retroactively switch all `perf` releases to shell interpreter from
store.