FB: sa1100: remove global sa1100fb_.*_power function pointers

Now that we have platform data contained within the individual board
code, we can get rid of the global function pointers, placing them
inside the platform data instead.

Acked-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>