platform/x86: fujitsu-laptop: use brightness_set_blocking for LED-setting callbacks

All LED-setting functions in fujitsu-laptop are currently assigned to
the brightness_set callback, which is incorrect because they can sleep
(due to their use of call_fext_func(), which in turn issues ACPI calls)
and the documentation (in include/linux/leds.h) clearly states they must
not.  Assign them to brightness_set_blocking instead and change them to
match the expected function prototype.

This change makes it possible to use Fujitsu-specific LEDs with "heavy"
triggers, like disk-activity or phy0rx.

Fixes: 3a407086 ("fujitsu-laptop: Add BL power, LED control and radio state information")
Fixes: 4f62568c ("fujitsu-laptop: Support radio LED")
Fixes: d6b88f64

 ("fujitsu-laptop: Add support for eco LED")
Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Acked-by: Jonathan Woithe <jwoithe@just42.net>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>