can: flexcan: remove ack_grp and ack_bit handling from driver

Since commit:

    048e3a34 can: flexcan: poll MCR_LPM_ACK instead of GPR ACK for stop mode acknowledgment

the driver polls the IP core's internal bit MCR[LPM_ACK] as stop mode
acknowledge and not the acknowledgment on chip level.

This means the 4th and 5th value of the property "fsl,stop-mode" isn't used
anymore. This patch removes the used "ack_gpr" and "ack_bit" from the driver.

Link: http://lore.kernel.org/r/20201006203748.1750156-15-mkl@pengutronix.de


Fixes: 048e3a34 ("can: flexcan: poll MCR_LPM_ACK instead of GPR ACK for stop mode acknowledgment")
Cc: Joakim Zhang <qiangqing.zhang@nxp.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>