kleaf: simplify kmi_symbol_list search logic.

Instead of specifying
  --in-dir=$ROOT_DIR/$KERNEL_DIR $(rel_path <src> $ROOT_DIR/$KERNEL_DIR)
use
  --in-dir=$ROOT_DIR <src>

This ensures that it works when $ROOT_DIR/$KERNEL_DIR
does not exist (because rel_path requires paths to exist).
This is the case in particular when the symbol list file
is outside of the $KERNEL_DIR for testing.

Test: see next CL

Change-Id: I4a0e8ef46d84c8006d9707167363b530f3aa16ca
1 file changed