The external Bus Unit (EBU) can control different flash devices, but
these NAND flash commands have to be atomic and should not be
interrupted in between. Lock the EBU from the beginning of the command
till the end by moving the lock to the chip select.
Signed-off-by: NJohn Crispin <john@phrozen.org>
Signed-off-by: NHauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: NBoris Brezillon <boris.brezillon@free-electrons.com>