mtd: nand: atmel: Relax tADL_min constraint

Version 4 of the ONFI spec mandates that tADL be at least 400 nanoseconds,
but, depending on the master clock rate, 400 ns may not fit in the tADL
field of the SMC reg. We need to relax the check and accept the -ERANGE
return code.

Note that previous versions of the ONFI spec had a lower tADL_min (100 or
200 ns). It's not clear why this timing constraint got increased but it
seems most NANDs are fine with values lower than 400ns, so we should be
safe.

Fixes: f9ce2edd ("mtd: nand: atmel: Add ->setup_data_interface() hooks")
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>