pxafb: move parallel LCD timing setup into dedicate function

pxafb: move parallel LCD timing setup into dedicate function

the new_regs stuff has been removed, and all the setup (modification to those
fbi->reg_*) is protected with IRQ disabled

   * disable IRQ is too heavy here, provided that no IRQ context will
     touch the fbi->reg_* and the only possible contending place is
     in the CPUFREQ_POSTCHANGE (task context), a mutex will be better,
     leave this for future improvement

Signed-off-by: eric miao <eric.miao@marvell.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>