Fix a buggy while loop expression, that, due to '==' operator's
precedence (higher than that of '&') was always evaluating to false
rendering busy loop into a no-op.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>