Reverts change in commit daf534d
Reverts change in commit daf534d

Commit daf534d from PR #457 breaks the build. This may reintroduce a
clang-analyse warning, but this is the wrong fix for that.

The fix removed a call to mbedtls_ecp_curve_info_from_grp_id() to find
the curve info. This fix adds that back in.

NXPmicro/mbedtls,NXPmicro/mbedtls,ARMmbed/mbedtls,NXPmicro/mbedtls,Mbed-TLS/mbedtls,NXPmicro/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls