soc: qcom: glink_smd_xprt: Fix read operation in streaming channel

The SMD Transport plugin checks for the packet size, then requests for
an rx intent of that size and reads the available data. In the case of
streaming SMD channels, the available data may become greater than the
packet size. This causes the data read operation to overflow the
receive buffer.

Limit the data read to the size of the rx intent.

CRs-Fixed: 942285
Change-Id: Id5377a7ccf19af1fe4c84c0dd735a739d03c9746
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>