automation/console.exp: do not assume expect is always at /usr/bin/

Instead use env to find the location of expect.

Additionally do not use the -f flag, as it's only meaningful when passing
arguments on the command line, which we never do for console.exp.  From the
expect 5.45.4 man page:

> The -f flag prefaces a file from which to read commands from.  The flag
> itself is optional as it is only useful when using the #! notation (see
> above), so  that other arguments may be supplied on the command line.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

automation/scripts/console.exp

@@ -1,4 +1,4 @@
-#!/usr/bin/expect -f
+#!/usr/bin/env expect
 
 if {[info exists env(TEST_TIMEOUT_OVERRIDE)]} {
     set timeout $env(TEST_TIMEOUT_OVERRIDE)