[ARM] 4952/1: magician: add LCD detection, LCD power switching, update pxafb settings

All magician devices I've encountered so far have featured the Toppoly
TD028STEB1 display, so the Samsung LTP280QV support is untested.
The power-on sequence is not correct because pxafb doesn't yet support
enabling the LCD controller in the middle of the it.

Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>