serial: 8250_exar: Remove old exar_ee_read() and other unneeded code

Remove the old exar_ee_read() and associated helper functions.
Remove defines that are no longer needed after the switch to using the
eeprom_93cx6 driver.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Parker Newman <pnewman@connecttech.com>
Link: https://lore.kernel.org/r/ed756c48965a95ce3384ebb7fe2441b4928b4510.1727880931.git.pnewman@connecttech.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>