scripts/link-vmlinux.sh: fix error message presentation

This comes out as

   Try make KALLSYMS_EXTRA_PASS=1 as a workaround

but we want quotes:

   Try "make KALLSYMS_EXTRA_PASS=1" as a workaround

Link: https://lkml.kernel.org/r/202303042034.Cjc7JTd0-lkp@intel.com


Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>