refinfra: update mbedtls version to v3.6.2

With TF-a commit '7dc43344' "update-mbedtls-to-3.6.2" into integration
TF-A expects the mbdeTLS library to be at v3.6.2. Update the manifests
to meet this requirement.

Signed-off-by: Raghuram Thammiraju <raghuram.thammiraju@arm.com>
Change-Id: Iae6e59430757c3c5799950f3416f4e7ae5f9d8ea