This aligns spinand_wait() with the linux kernel. Instead of calling into
spi_mem_poll_status() which is not implemented in U-Boot, we code the
polling logic and make sure that schedule() is called periodically.
Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>