Bluetooth: Set P-bit for SREJ frame only if there are I-frames to ack
SREJ frame with P-bit set acknowledges I-frames numbered up to
(ReqSeq - 1). With this patch P-bit in SREJ is set only when there are
some I-frames to ack.
This fixes ambiguous situation when lost of I-frame with TxSeq=0 would
result in sending SREJ acking all previous I-frames.
Consider following scenario:
TxWindow=3
HostA: sent I-frame TxSeq=0
HostA: sent I-frame TxSeq=1
HostA: sent I-frame TxSeq=2
HostB: missed I-frame TxSeq=0
HostB: received I-frame TxSeq=1
HostB: sent SREJ ReqSeq=0 Pbit=1
HostA: received SREJ ReqSeq=0 Pbit=1 <- All I-frames acked or not?
...