The egress timestamp FIFO/circular buffer work different on TJA1120 than
TJA1103.

For TJA1103 the new timestamp should be manually moved from the FIFO to
the hardware buffer before checking if the timestamp is valid.

For TJA1120 the hardware will move automatically the new timestamp
from the FIFO to the buffer and the user should check the valid bit, read
the timestamp and unlock the buffer by writing any of the buffer
registers(which are read only).

Another change for the TJA1120 is the behaviour of the EGR TS IRQ bit.
This bit was a self-clear bit for TJA1103, but now should be cleared
before reading the timestamp.
Signed-off-by: Radu Pirea (NXP OSS) <radu-nicolae.pirea@oss.nxp.com>
Link: https://lore.kernel.org/r/20230731091619.77961-8-radu-nicolae.pirea@oss.nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>