can: xilinx_can: Fix flags field initialization for axi can

AXI CANIP doesn't support tx fifo empty interrupt feature(TXFEMP),
update the flags filed in the driver for AXI CAN case accordingly.

Fixes: 3281b380 ("can: xilinx_can: Fix flags field initialization for axi can and canps")
Reported-by: Anssi Hannula <anssi.hannula@bitwise.fi>
Signed-off-by: Appana Durga Kedareswara rao <appana.durga.rao@xilinx.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>