[PATCH] bcm43xx: voluntary preemtion in the calibration loops

This patch adds voluntary preemption points into the
PHY calibration loops to allow non-CONFIG_PREEMPT machines
to not suffer from huge delays.
CONFIG_PREEMPT machines are already fine, because all this
code is run in non-atomic process context.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>