CR50: point multiply should check point for curve membership
CR50: point multiply should check point for curve membership

_cpri__EccPointMultiply should check whether the provided
point is on the curve prior to doing a multiply.

BRANCH=none
BUG=chrome-os-partner:43025,chrome-os-partner:47524
TEST=TCG test CPCTPM_TC2_4_13_01_01 passes

Change-Id: Ia92494070c62f7e03b395975138c0c8446a7284d
Signed-off-by: nagendra modadugu <5dc366ddbf8fb5981f46478e8436ef712a08b71b@google.com>
Reviewed-on: https://chromium-review.googlesource.com/341112
Commit-Ready: Nagendra Modadugu <5dc366ddbf8fb5981f46478e8436ef712a08b71b@google.com>
Tested-by: Nagendra Modadugu <5dc366ddbf8fb5981f46478e8436ef712a08b71b@google.com>
Reviewed-by: Marius Schilder <d423f2980be0298efdef7df239b147d21d472f26@chromium.org>

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