xilinx_axienet: Fix bit mask code

Obviously the code wanted to mask the lower bits but failed to do so
because of a missing "<".

cppcheck detected a conditional expression which was always true (1 < 7).

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
xilinx_axidma: Do not set DMA .notify to NULL after notify

If a stream notify function is not ready, it may re-populate the notify call-
back to indicate it should be re-polled later. This break in this usage, as
immediately following the notify() call, .notify is set to NULL. reverse the
ordering of the notify call and NULL assignment accordingly.

[PC: Reworked commit message]

Signed-off-by: Wendy Liang <jliang@xilinx.com>
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>