MLK-17108-4 usb: typec: tcpci: correct read data msg length

MLK-17108-4 usb: typec: tcpci: correct read data msg length

Per tcpci spec, the TCPC_RX_BYTE_CNT is the number of bytes in the
RX_BUFFER_DATA_OBJECTS plus three (for the RX_BUF_FRAME_TYPE and
RX_BUF_HEADER), so after read out the header, we should only read
TCPC_RX_BYTE_CNT-3 bytes for data if this is a data message.

Acked-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Li Jun <jun.li@nxp.com>
Signed-off-by: Vipul Kumar <vipul_kumar@mentor.com>