expect: Replace tclsh with tclsh8 in the scripts used in the Expect

expect: Replace tclsh with tclsh8 in the scripts used in the Expect

Before upgrading to Tcl 9.0.0, running `tclsh` worked successfully, and
the recipe configuration was as follows: ln -sf ./tclsh${VER}
${D}${bindir}/tclsh

After upgrading to Tcl 9.0.0, to ensure compatibility with Expect, Tcl
8.6.15 was additionally included. To distinguish between the two
versions, the configuration was set as: ln -sf ./tclsh${VER}
${D}${bindir}/tclsh8

Therefore, the input needs to be `tclsh8` to work properly, which means
the `tclsh` references in the Expect-related scripts need to be changed
to `tclsh8`.

Signed-off-by: Jiaying Song <jiaying.song.cn@windriver.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>