MINOR: quic: remove qc_treat_rx_crypto_frms()

MINOR: quic: remove qc_treat_rx_crypto_frms()

This commit removes qc_treat_rx_crypto_frms(). This function was used in
a single place inside qc_ssl_provide_all_quic_data(). Besides, its
naming was confusing as conceptually it is directly linked to quic_ssl
module instead of quic_rx.

Thus, body of qc_treat_rx_crypto_frms() is inlined directly inside
qc_ssl_provide_all_quic_data(). Also, qc_ssl_provide_quic_data() is now
only used inside quic_ssl to its scope is set to static. Overall, API
for CRYPTO frame handling is now cleaner.