imxfb: remove ifdefs

Here are some small fixes for the imxfb framebuffer driver:

 - remove ifndef for MX1FS2 platform which is not present in the kernel.
 - REV, CLS, PS and SPL_SPR are only needed with some sharp displays.
   Only setup the corresponding io pins when such a display is connected.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>