net: qrtr: fifo: Add bounds check on tx path

Add bounds check on values read from shared memory in the tx path. In
cases where the VM is misbehaving, the qrtr transport should exit and
print a warning when bogus values may cause out of bounds to be read.

Change-Id: I7ebef28ed8eba4c4da0b32d5114365bbe6bea390
Signed-off-by: Sarannya S <quic_sarannya@quicinc.com>