CC312: Add mbedtls_hardware_poll for PSA driver

Add its own mbedtls_hardware_poll to register entropy for PSA driver.
This will get rid of libcrypto_service_cc312_mbedtls_api.a library and
save about 0.5KB in RO size.

Signed-off-by: Summer Qin <summer.qin@arm.com>
Change-Id: Ie0fed9ee122d3a9ec7489f1ffe69ac76a0a5fc3c
1 file changed