[PARISC] Use work queue in LED/LCD driver instead of tasklet.

2.6.12-rc1-pa6 use work queue in LED/LCD driver instead of tasklet.

Main advantage is it allows use of msleep() in the led_LCD_driver to
"atomically" perform two MMIO writes (CMD, then DATA).
Lead to nice cleanup of the main led_work_func() and led_LCD_driver().
Kudos to David for being persistent.

From: David Pye <dmp@davidmpye.dyndns.org>
Signed-off-by: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>