cr50: add p256 public RMA key
cr50: add p256 public RMA key

The blob includes 65 bytes of the public key and one byte of the key
ID, 66 bytes total.

BRANCH=cr50, cr50-mp
BUG=b:73296606, b:73647182
TEST=none

Change-Id: I0adf844a487776b0a93eae404f7bc74566d003fc
Signed-off-by: Vadim Bendebury <5515d6d2d0829cbe0dd0dcf2094aaded06d58514@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1099730
Reviewed-by: Randall Spangler <62698fdbb84d1779579ee80c3f39fac22017e5bc@chromium.org>

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