feat(juno): add mbedtls_asn1_get_len symbol in ROMlib

mbedtls_asn1_get_len() will be needed by the X.509 parser in an
upcoming patch.

Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Change-Id: I5609da000bbfc8a1503c298550ae3b0ba881fc96
1 file changed