serial: 8250_keba: Add ICR defines
Add defines for better readability of the Indexed Control Register (ICR)
access. In enhanced mode SCR and LSR registers are used for ICR access.
The behavior of these register is different in this mode and that shall
be documented with dedicated defines.
Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Gerhard Engleder <eg@keba.com>
Link: https://patch.msgid.link/20251216193726.55449-3-gerhard@engleder-embedded.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>