docs/fingerprint: Update JLink installation instructions
docs/fingerprint: Update JLink installation instructions

JLink can now be installed in the chroot with portage.

BRANCH=none
BUG=b:178132109
TEST=view in gitiles

Signed-off-by: Tom Hughes <fc5c12f30a5ed2baa0581f44ee14ad1eb7b20d83@chromium.org>
Change-Id: Ief8e64e10c9ff1f8cfdc528dce6bca34d3973f0c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3369648
Reviewed-by: Josie Nordrum <15709ebcc9b54f095b12491b186117e19e6ed974@google.com>
Reviewed-by: Bobby Casey <a3c107f0b4efaee07148ab0813ba992bba562a69@google.com>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec