A read id operation followed by 0x00 reads the device ID while
a read id operation followed by 0x20 reads the possible ONFI identifier.

As the READID function did not propagate the second id parameter but had
a hard-coded call for 0x90 0x00, reading the ONFI identifier was not
possible and thus chips werde not detected (tested with
MT29F8G08ABABAWP)
Signed-off-by: Enrico Jorns <ejo@pengutronix.de>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>