feat(fvp): 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: I14310c80033a1142a94c0c4b54d63331479b643d
diff --git a/plat/arm/board/fvp/jmptbl.i b/plat/arm/board/fvp/jmptbl.i
index 927ffef..dc8032f 100644
--- a/plat/arm/board/fvp/jmptbl.i
+++ b/plat/arm/board/fvp/jmptbl.i
@@ -43,6 +43,7 @@
 mbedtls mbedtls_asn1_get_bitstring_null
 mbedtls mbedtls_asn1_get_bool
 mbedtls mbedtls_asn1_get_int
+mbedtls mbedtls_asn1_get_len
 mbedtls mbedtls_asn1_get_tag
 mbedtls mbedtls_free
 mbedtls mbedtls_md