Fix AxiStreamFrame default for self.byte_lanes from 1 to all.

If I connect a AXIS source to an AXIS sink, the #byte_lanes is incorrectly 1 rather than all lanes enabled.
self.source = AxiStreamSource(AxiStreamBus.from_prefix(dut, "sink"), dut.clk, dut.reset)

Root cause is AxiStreamFrame assumes byte width 1 without TKEEP, but it should default to self.width // 8
because the AXIS specification mentions "when TKEEP is absent, TKEEP defaults to all bits HIGH" and "The width of the data payload is an integer number of bytes."

Fix: https://github.com/alexforencich/cocotbext-axi/blob/master/cocotbext/axi/axis.py#L290

self.byte_lanes = 1
self.byte_lanes = self.width // 8

Relevant AXIS Specification:
https://developer.arm.com/documentation/ihi0051/a/Default-Signaling-Requirements/Default-value-signaling/Optional-TKEEP-and-TSTRB?lang=en

Signed-off-by: Leon Woestenberg <leon@sidebranch.com>

cocotbext/axi/axis.py

@@ -287,7 +287,7 @@ class AxiStreamBase(Reset):
         self.queue_occupancy_frames = 0
 
         self.width = len(self.bus.tdata)
-        self.byte_lanes = 1
+        self.byte_lanes = self.width // 8
 
         if self._valid_init is not None and hasattr(self.bus, "tvalid"):
             self.bus.tvalid.setimmediatevalue(self._valid_init)