Large SPI-NOR (>2MB) chips reuire more than 40 seconds to perform
all-chip erase. This patch adapts
09b6a37 from Linux kernel, which
implements simple heuristics in order to calculate appropriate wait
time (see orignal commit's description for more details of the fix)
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>