nfc: st-nci: Remove pr_err in rcv_queue when ndlc header is unknown

spi phy needs to use ndlc_recv at every spi transaction causing
"unknown packet control byte" error message each time the header
is 00. Make this silent.

Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>